Tennessee Onion Casserole

Ingredients

• 3 lb sweet onions (peeled and sliced 1/4 inch thick on a mandolin)
• 2 tsp salt
• 1 tsp black pepper
• 1 tsp smoked paprika
• 1 tsp granulated garlic
• 1 tsp dry mustard
• 2 tsp brown sugar (light or dark)
• 0.5 tsp cayenne pepper
• 1 tsp fresh thyme leaves (stripped from stems)
• 2 tbsp olive oil (good quality)
• 4 oz mild cheddar cheese (freshly grated, divided (Tillamook recommended))
• 4 oz Gruyère cheese (freshly grated, divided)
• 0.5 cup Pecorino Romano cheese (freshly grated; can substitute Parmigiano-Reggiano or Grana Padano)
• 3 tbsp unsalted butter (cut into small pieces)

Steps

1. 1

   Preheat your oven to 350°F (175°C). Grease a 13x9-inch baking dish.

2. 2

   Peel the 3 pounds of sweet onions and slice them into uniform 1/4-inch thick rings using a mandolin. Toss the slices to break up the rings.

3. 3

   In a small bowl, combine the salt, black pepper, smoked paprika, granulated garlic, dry mustard, brown sugar, cayenne, and fresh thyme leaves to create the spice blend.

4. 4

   Place the onions in a large bowl and drizzle with 2 tablespoons of olive oil. Toss until the onions are well coated.

5. 5

   Sprinkle half of the spice mixture over the onions and toss by hand. Add the remaining spice mixture and toss again until evenly distributed.

6. 6

   Place half of the seasoned onions into the prepared baking dish in an even layer.

7. 7

   Sprinkle 2 ounces of the grated cheddar and 2 ounces of the grated Gruyère over the first layer of onions.

8. 8

   Add the remaining onions as a second layer on top of the cheese.

9. 9

   Top the second layer of onions with the remaining 2 ounces of cheddar and 2 ounces of Gruyère.

10. 10

    Evenly sprinkle the 1/2 cup of Pecorino Romano over the top of the casserole.

11. 11

    Dot the top of the cheese with the 3 tablespoons of butter pieces.

12. 12

    Cover the dish tightly with aluminum foil.

13. 13

    Bake in the preheated oven for 45 minutes.

14. 14

    Remove the foil and continue baking for another 30 minutes until the cheese is bubbly and golden and the onions are silky.

Notes

The key to this dish is slicing the onions thin and uniform so they melt into a silky texture rather than remaining crunchy. You can substitute Sharp Cheddar for Mild if you prefer a stronger flavor.

Nutrition per serving

• side dish
• casserole
• vegetarian
• baked
• holiday
• comfort food