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Tennessee Onions

Sweet onions become meltingly tender beneath a blanket of seasoned butter and gooey cheese, creating layers of savory richness that pairs perfectly with grilled steaks, smoked meats, or any comfort food meal.
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Prep Time 15 minutes
Cook Time 1 hour
Total Time 1 hour 15 minutes
Servings: 8 servings
Course: Side Dishes
Cuisine: Southern American
Calories: 285
Ingredients Equipment Method Notes

Ingredients
  

Main
  • 4 large sweet onions Vidalia preferred, about 3 pounds total, sliced into 1/2 inch thick rounds
  • 1/2 cup unsalted butter melted
  • 1 packet dry onion soup mix about 1 ounce
  • 2 cups shredded mozzarella cheese
  • 1 cup shredded Parmesan cheese freshly grated preferred
  • Fresh cracked black pepper to taste

Equipment

  • 9x13 inch baking dish
  • Sharp chef knife
  • Cutting board
  • Small saucepan or microwave safe bowl
  • Measuring cups and spoons
  • Box grater or pre shredded cheese
  • Aluminum foil
  • Oven mitts

Method
 

  1. Preheat your oven to 350 degrees Fahrenheit and position a rack in the center.
  2. Peel your sweet onions and slice them into 1/2 inch thick rounds, keeping the rings intact as much as possible.
  3. Melt the butter in a small saucepan over low heat or in the microwave. Stir in the entire packet of onion soup mix until well combined.
  4. Arrange half of the sliced onions in a single layer in your 9x13 inch baking dish.
  5. Drizzle half of the seasoned butter mixture evenly over the first layer of onions. Sprinkle half of the mozzarella and half of the Parmesan cheese over the top.
  6. Arrange the remaining onion slices over the cheese layer. Pour the rest of the butter mixture over the onions, then top with the remaining mozzarella and Parmesan cheeses.
  7. Cover the baking dish tightly with aluminum foil and bake for 45 minutes, allowing the onions to soften and release their natural juices.
  8. Remove the foil and continue baking for an additional 15 minutes until the cheese turns golden and bubbly.
  9. Let the casserole rest for 5 minutes before serving. Season with fresh cracked black pepper to taste.

Notes

For an extra crispy, golden cheese crust, switch your oven to broil for the final 2 to 3 minutes, watching carefully to prevent burning. You can assemble this dish up to 24 hours in advance and refrigerate covered, adding 10 to 15 minutes to the baking time. Store leftovers in an airtight container for up to 4 days in the refrigerator.