Tennessee Cheesy Baked Onions is a rich, savory casserole that layers thinly sliced sweet onions with a blend of cheddar, mozzarella, and parmesan cheese, seasoned with garlic and paprika. It's a warming comfort-food side dish with melted cheese and buttery depth.
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Preheat your oven to 350°F (175°C).
Thinly slice the sweet onions using a mandoline or a sharp knife.
In a large bowl, combine the sliced onions with garlic powder, dried parsley, paprika, white pepper, and cayenne pepper. Season with seasoned salt and black pepper.
Toss well to ensure the onions are evenly coated with the spices.
Grease a 9x13-inch baking dish with butter or non-stick cooking spray.
Spread half of the seasoned onions in an even layer in the prepared dish.
Sprinkle half of the shredded cheddar and half of the shredded mozzarella over the onions.
Top with the remaining onions, followed by the rest of the cheddar, mozzarella, and all of the grated Parmesan cheese.
Arrange the pats of unsalted butter evenly over the top of the cheese. Finish with another light sprinkle of seasoned salt.
Cover the baking dish tightly with aluminum foil.
Bake for 30-40 minutes, or until the onions are tender.
Carefully remove the foil and return the dish to the oven. Bake uncovered for another 15-20 minutes, until the top is golden brown and bubbly.
Let it rest for a few minutes, then garnish with fresh parsley before serving.
Store covered in the refrigerator for up to 3 days. Reheat covered at 325°F for 15–20 minutes until warmed through.
9x13 inch baking dish · mandoline or sharp knife
Yes. Assemble the casserole up to 24 hours ahead, cover with foil, and refrigerate. Add 5–10 minutes to baking time if baking from cold.
Sweet onions like Vidalia or Texas 1015 are ideal—they caramelize gently and add natural sweetness. Yellow onions work too but are more pungent.
Slice them 1/4 inch thick so they cook evenly and soften without falling apart during layering.
Yes, but freshly shredded cheese melts more smoothly. Pre-shredded varieties contain anti-caking agents that can make the texture slightly grainy.
Dairy-free shredded cheese blends exist but won't melt as richly. This recipe is best made with real cheese for optimal texture and flavor.
