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Tennessee Onion Casserole Recipe

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4 from 24 reviews

Tender, sweet onions are layered with cheddar, Gruyère, and Parmesan, then baked with smoky, gently spiced seasonings until bubbling and golden. This comforting Tennessee onion casserole is an easy, savory side dish for holidays, potlucks, or weeknight dinners.

Ingredients

For the onions and seasoning

  • 3 pounds sweet onions
  • 2 tablespoons olive oil
  • 2 teaspoons salt
  • 2 teaspoons brown sugar
  • 1 teaspoon black pepper
  • 1 teaspoon smoked paprika
  • 1 teaspoon garlic powder
  • 1 teaspoon mustard powder
  • 1 teaspoon fresh thyme, finely chopped
  • ½ teaspoon cayenne pepper

For the cheese topping

  • 4 ounces shredded cheddar cheese
  • 4 ounces shredded Gruyère cheese
  • ½ cup grated Parmesan cheese
  • 3 tablespoons butter, cut into small pieces
  • Nonstick cooking spray, as needed

Instructions

  1. Preheat the oven: Heat the oven to 350°F (175°C). Lightly coat a 9-by-13-inch baking dish with nonstick cooking spray.
  2. Slice the onions: Peel the onions and slice them very thinly, using a mandoline if available. Transfer the slices to a large bowl.
  3. Coat the onions with oil: Drizzle the olive oil over the onion slices and toss until they are evenly coated.
  4. Mix the seasonings: In a small bowl, combine the salt, brown sugar, black pepper, smoked paprika, garlic powder, mustard powder, chopped thyme, and cayenne pepper. Stir well.
  5. Season the onions: Sprinkle the seasoning mixture over the onions and toss until the slices are evenly coated.
  6. Layer the first half: Spread half of the seasoned onions in the prepared baking dish. Sprinkle over 2 ounces of cheddar and 2 ounces of Gruyère.
  7. Finish layering: Add the remaining onions in an even layer, then top with the remaining cheddar and Gruyère.
  8. Add the Parmesan and butter: Sprinkle the Parmesan evenly over the casserole. Dot the top with the small pieces of butter.
  9. Bake covered: Cover the dish tightly with foil and bake for 45 minutes, until the onions have softened.
  10. Bake uncovered: Carefully remove the foil and continue baking for 30 minutes, until the top is golden and the casserole is bubbling.
  11. Serve: Remove the casserole from the oven and serve hot.

Notes

  • Slice the onions as thinly and evenly as possible so they soften consistently while baking.
  • Use a mandoline carefully, with its hand guard, to make quick work of slicing.
  • For the best melt, shred the cheddar and Gruyère from blocks rather than using pre-shredded cheese.
  • Let the casserole rest for a few minutes after baking; it will be very hot and will settle slightly as it cools.

Find it online: https://recipethrive.com/tennessee-onion-casserole-recipe/