Cheesy Baked Tennessee Onions Recipe

Tennessee Onions is a rich and comforting Southern casserole made with layers of sweet onions and plenty of melted cheese. As the onions bake, they become soft, tender, and slightly caramelized, blending perfectly with sharp cheddar, smoky Gouda, and savory Parmesan. This easy baked onion casserole is the perfect side dish for holidays, potlucks, burgers, or weeknight dinners when you want something simple but incredibly flavorful.

Why You’ll Love Tennessee Onions

• It’s incredibly cheesy and comforting. Every bite is packed with gooey cheddar, smoky Gouda, and savory Parmesan. The cheese melts into the tender onions and creates the most irresistible texture. If you love melty, golden-brown cheese, this casserole will absolutely satisfy.

• The flavor is sweet, savory, and slightly smoky. The onions soften and develop a natural sweetness as they bake. The blend of mustard powder, garlic, smoked paprika, and a hint of cayenne adds depth without overpowering the dish. It tastes rich and well-balanced with very simple ingredients.

• It’s surprisingly easy to make. There’s no complicated prep or fancy techniques involved. You just slice, season, layer, and bake. The oven does most of the work for you.

• It’s perfect for holidays and gatherings. This casserole makes a generous amount and feeds a crowd. It pairs beautifully with grilled meats, burgers, or roasted chicken. It’s also a unique side dish that always gets people talking.

• It uses simple pantry ingredients. Everything in this recipe is easy to find at the grocery store. No special or hard-to-find items are required. That makes it convenient for both weeknight dinners and last-minute entertaining.

Ingredients For Tennessee Onions

• Sweet Onions – These are the star of the dish. Sweet onions like Vidalia become tender and slightly caramelized as they bake, giving the casserole its signature flavor and soft texture.

• Kosher Salt – Enhances the natural sweetness of the onions and balances the richness of the cheese.

• Dry Mustard Powder – Adds a subtle tangy depth that complements the cheese beautifully without making the dish taste mustardy.

• Garlic Powder – Brings savory flavor throughout the casserole and pairs perfectly with the onions.

• Smoked Paprika – Gives a gentle smoky note that makes the flavor more complex and comforting.

• Cayenne Pepper – Optional, but adds a mild kick for those who enjoy a little heat.

• Mild Cheddar Cheese – Melts smoothly and creates that classic gooey, cheesy texture in every layer.

• Smoked Gouda or Smoked Cheddar – Adds extra richness and a delicious smoky flavor that makes this casserole stand out.

• Parmesan Cheese – Sprinkled on top for a savory, slightly salty finish and beautiful golden color.

• Unsalted Butter – Dotted on top to add richness and help everything bake into a bubbly, flavorful casserole.

• Fresh Parsley – Optional garnish that adds a pop of freshness and color before serving.

For the exact measurements of the ingredients, see the printable recipe card at the bottom of this article.

Kitchen Tools You Need To Make Tennessee Onions

• 9×13-inch Baking Dish – This size dish allows the onions to bake in even layers and ensures the casserole cooks evenly.

• Large Mixing Bowl – You’ll need this to toss the onion rings with the seasonings so everything is well coated.

• Measuring Spoons – Important for accurately measuring the spices and salt for balanced flavor.

• Measuring Cups – Useful for portioning out the shredded cheeses and Parmesan.

• Aluminum Foil – Covers the casserole during the first part of baking so the onions soften properly before the cheese browns.

How To Make Tennessee Onions

• Start by heating your oven to 350°F and lightly greasing your baking dish with cooking spray.

• Separate the sliced sweet onions into rings and place them in a large bowl. Sprinkle in the salt, mustard powder, garlic powder, smoked paprika, and cayenne, then toss until the onions are evenly seasoned.

• Spread half of the seasoned onion rings across the bottom of the prepared baking dish in an even layer.

• Sprinkle half of the shredded cheddar and half of the smoked Gouda over the onions.

• Add the remaining onions on top, then finish with the rest of the cheddar, smoked Gouda, and all of the Parmesan cheese.

• Dot the top evenly with small pieces of butter to add richness as it bakes.

• Cover the dish tightly with foil and bake until the onions are soft and tender.

• Remove the foil and continue baking until the cheese is melted, bubbly, and lightly browned on top. Garnish with fresh parsley before serving if desired.

Serving Suggestions

• Serve Tennessee Onions as a rich side dish alongside air-fried steak, roasted chicken breast, or pan-seared pork chops. The cheesy onions pair beautifully with simple proteins and add big flavor to the plate.

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• Spoon it over grilled hamburgers or grilled cheese sandwiches for an extra indulgent twist. The melted cheese and tender onions create an incredible topping.

• Add it to a holiday spread with baked ham, turkey breast, or prime rib roast. It fits perfectly on Thanksgiving, Christmas, or Easter tables.

• Serve it with crusty mini baguettes to soak up the cheesy, buttery goodness. It also works well with homemade cornbread for a true Southern-style meal.

• Enjoy it as a vegetarian main dish with a tomato, avocado, and lettuce salad on the side to balance the richness.

Tips For Success

• Use sweet onions for the best flavor and texture. Sweet onions like Vidalia become soft, tender, and slightly caramelized as they bake. If you use regular yellow onions, the flavor may be sharper and less sweet. The natural sweetness really balances the richness of the cheese.

• Slice the onions evenly. Try to keep the slices about 1/4-inch thick so they cook at the same rate. If some slices are too thick, they may stay slightly firm. If they are too thin, they can become overly soft and watery.

• Separate the onion rings before seasoning. This helps the spices coat every piece evenly. If the onions stay clumped together, some parts may be under-seasoned. Tossing thoroughly makes a big difference in flavor.

• Don’t skip covering the dish for the first part of baking. The foil traps steam, which helps soften the onions properly. If you bake it uncovered the whole time, the cheese may brown too quickly before the onions are tender. The two-stage baking process ensures perfect texture.

• Let the casserole rest for a few minutes before serving. Right out of the oven, it will be very bubbly and loose. Allowing it to sit for 5 to 10 minutes helps everything settle slightly. This makes it easier to serve and improves the overall texture.

• Shred your own cheese if possible. Pre-shredded cheese contains anti-caking agents that can affect how smoothly it melts. Freshly shredded cheese melts more evenly and gives you that creamy, gooey finish. It’s a small extra step that makes a noticeable difference.

• Watch closely during the final bake. Once you remove the foil, the cheese can brown quickly. You want golden brown spots, not burnt edges. Keep an eye on it during the last 10 minutes.

• Season to your taste. If you enjoy a little heat, don’t skip the cayenne. If you prefer it mild, you can leave it out. This recipe is very forgiving and easy to adjust.

Variations And Substitutions

• Swap the cheeses to change the flavor profile. While cheddar and smoked Gouda create a rich and slightly smoky taste, you can experiment with Monterey Jack, mozzarella, Colby Jack, or even provolone. Monterey Jack will make it extra creamy and mild. Mozzarella will give you that stretchy, melty texture. If you love bold flavor, try sharp cheddar instead of mild.

• Make it extra smoky. If you really enjoy smoky flavor, use smoked cheddar instead of regular cheddar. You can also increase the smoked paprika slightly for a deeper smoky note. Just be careful not to overpower the sweetness of the onions. Balance is key.

• Add more heat if you like spice. The cayenne pepper is optional, but you can increase it for more kick. You could also add a pinch of red pepper flakes. If serving guests, keep it mild and offer hot sauce on the side.

• Make it richer. For an even more indulgent casserole, you could add a few tablespoons of heavy cream before baking. The cream will blend with the melted cheese and create a slightly saucier texture. This works especially well if serving it as a standalone side dish.

• Try different onions. Sweet onions are ideal for their mild flavor. However, you can use yellow onions if that’s what you have on hand. Keep in mind they will taste slightly stronger and less sweet. A mix of sweet and yellow onions can also work nicely.

• Make it dairy-free. Substitute plant-based butter and dairy-free shredded cheese alternatives. The texture may vary slightly depending on the brand used. Choose a dairy-free cheese that melts well for best results.

• Add protein to turn it into a main dish. You can layer in cooked crumbled bacon, sliced sausage, or shredded rotisserie chicken between the onion layers. This makes the casserole more filling and transforms it into a hearty main course.

• Add herbs for freshness. Fresh thyme pairs beautifully with onions and cheese. You can sprinkle a small amount between the layers. Chopped chives also make a nice finishing touch.

• Make it ahead-friendly. Assemble the casserole earlier in the day, cover, and refrigerate. When ready to bake, allow it to sit at room temperature for about 20 minutes before placing it in the oven. This makes entertaining much easier.

Storage and Reheating

• Allow the Tennessee Onions to cool completely before storing. This helps prevent excess moisture from building up in the container.

• Store leftovers in an airtight container in the refrigerator for up to 4 days. The flavors actually deepen as it sits, making it just as delicious the next day.

• To reheat in the oven, place the desired portion in an oven-safe dish and cover with foil. Warm at 350°F until heated through. Covering helps prevent the cheese from over-browning.

• To reheat in the microwave, place a portion on a microwave-safe plate and heat in 30-second intervals until warmed through. Keep in mind the microwave may soften the texture slightly more than the oven.

• If the casserole seems a bit dry after refrigeration, you can add a small pat of butter on top before reheating to refresh the richness.

Frequently Asked Questions

Can I use regular yellow onions instead of sweet onions?

Yes, you can use yellow onions if that’s what you have available. Keep in mind that yellow onions have a stronger, sharper flavor compared to sweet onions like Vidalia. Since onions are the main ingredient in this recipe, the type you choose will noticeably affect the final taste. Sweet onions create a milder, slightly caramelized flavor that balances beautifully with the cheese. If using yellow onions, the casserole may have a more pronounced onion bite, but it will still be delicious.

Can I make Tennessee Onions ahead of time?

Yes, this casserole is very make-ahead friendly. You can fully assemble it earlier in the day, cover it tightly, and store it in the refrigerator before baking. When you’re ready to cook, let it sit at room temperature for about 20 minutes so the dish isn’t going straight from cold to hot. Then bake as directed. This makes it perfect for holidays, gatherings, or busy weeknights when you want to prep in advance.

Why do I need to cover the casserole with foil at first?

Covering the dish during the first part of baking is important for texture. The foil traps steam, which helps soften the onions and allows them to become tender. If you skip this step, the cheese may brown too quickly before the onions are fully cooked. The two-step baking method ensures that the onions are soft and flavorful before the top gets golden and bubbly. Removing the foil at the end gives you that perfect browned cheese finish.

Can I freeze Tennessee Onions?

While you technically can freeze it, the texture may change slightly after thawing. Onions contain a lot of moisture, and freezing can cause them to become softer once reheated. The cheese may also separate a bit. If you do freeze it, store it in an airtight container and thaw overnight in the refrigerator before reheating. For best texture and flavor, this dish is best enjoyed fresh or within a few days of making it.

What should I serve with Tennessee Onions?

Tennessee Onions pairs beautifully with grilled meats like steak, chicken, pork chops, or burgers. It also works wonderfully as part of a holiday meal alongside ham or turkey. Because it’s rich and cheesy, it balances nicely with lighter sides like a crisp green salad or roasted vegetables. Some people even enjoy spooning it over burgers or serving it with crusty bread to soak up all the cheesy goodness. It’s a versatile dish that fits into many different menus.

Other Easy Onion Recipes

Homemade Onion Buns – Soft, fluffy homemade buns infused with savory onion flavor that are perfect for burgers, sandwiches, or serving warm with butter.

Battered Onion Rings – Crispy, golden battered onion rings with a crunchy coating and tender sweet onion inside.

Sautéed Mushrooms and Caramelized Onions – Tender mushrooms and sweet caramelized onions cooked together in a flavorful skillet side dish.

Pickled Red Onions – Tangy, vibrant quick-pickled red onions that add a bright pop of flavor to tacos, salads, and sandwiches.

Instant Pot Fajita Peppers and Onions – Perfectly tender peppers and onions made quickly in the Instant Pot for easy fajitas or Tex-Mex meals.

Grilled Onion Rounds with Marinade – Juicy grilled onion slices brushed with a simple marinade for a smoky, savory side dish.

Roasted Potatoes and Onions – Crispy roasted potatoes and tender onions baked together for an easy and comforting side dish.

More Side Dish Recipes

• Sweet Pineapple Casserole
• Simple Steamed Cauliflower
• Crispy Skillet Potatoes with Tomatoes