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Close-up of cheesy Tennessee Onions casserole with tender baked onion rings layered in melted cheddar and herbs.
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Tennessee Onions

This Tennessee Onions casserole is the ultimate cheesy Southern side dish. Sweet onions are layered with cheddar, smoked Gouda, and Parmesan, then baked until soft, bubbly, and golden brown. If you love caramelized onions and melty cheese, this easy baked onion recipe will become your new favorite comfort food.
Prep Time15 minutes
Cook Time1 hour 15 minutes
Total Time1 hour 30 minutes
Course: Casserole, Side Dish
Cuisine: Southern
Keyword: baked onions, cheesy onions, onion casserole, Southern side dish, Tennessee onions
Cooking Method: Oven
Diet: Gluten-Free, Vegetarian
Servings: 8
Calories: 233kcal
Author: MelanieCooks.com

Equipment

Ingredients

  • Cooking spray
  • 3 pounds sweet onions such as Vidalia, about 4 large, sliced crosswise into 1/4-inch rounds
  • 1 1/2 tsp kosher salt
  • 1 tsp dry mustard powder
  • 1 tsp garlic powder
  • 1 tsp smoked paprika
  • 1/4 tsp cayenne pepper optional
  • 4 ounces mild cheddar cheese shredded about 1 cup, divided
  • 4 ounces smoked Gouda or smoked cheddar cheese, shredded about 1 cup, divided
  • 1/3 cup Parmesan cheese grated
  • 4 tbsp butter unsalted, diced
  • 2 tbsp fresh parsley chopped, optional, for garnish

Instructions

  • Preheat the oven to 350°F and lightly coat a 9x13-inch baking dish with cooking spray.
  • Place the sliced onions in a large bowl, separate into rings, and toss with salt, mustard powder, garlic powder, smoked paprika, and cayenne until evenly coated.
  • Arrange half of the seasoned onions in an even layer in the baking dish.
  • Sprinkle with half of the cheddar and half of the smoked Gouda.
  • Top with the remaining onions, then sprinkle with the remaining cheddar, smoked Gouda, and all of the Parmesan.
  • Scatter the diced butter evenly over the top.
  • Cover tightly with foil and bake for 45 minutes, until the onions are tender and bubbling.
  • Remove the foil and bake for 30 more minutes, until the cheese is fully melted and browned in spots. Garnish with parsley if desired and serve hot.

Notes

  • Sweet onions work best because they soften beautifully and develop a mild, caramelized flavor while baking.
  • Watch closely during the final minutes of baking to prevent over-browning.

Nutrition

Calories: 233kcal | Carbohydrates: 14g | Protein: 10g | Fat: 16g | Saturated Fat: 10g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 4g | Trans Fat: 0.2g | Cholesterol: 48mg | Sodium: 771mg | Potassium: 255mg | Fiber: 2g | Sugar: 9g | Vitamin A: 664IU | Vitamin C: 10mg | Calcium: 288mg | Iron: 1mg