Tennessee Onions are a baked Vidalia onion side dish layered with butter, garlic, oregano, and three cheeses. As the onions bake, they soften and turn sweet underneath a bubbling layer of Italian-blend cheese, cheddar, and Parmesan.
Why Tennessee Onions Work
- Sweet onions: Vidalia onions soften into a mellow, naturally sweet base.
- Three cheeses: Italian blend, cheddar, and Parmesan give the top plenty of flavor and browning.
- Simple seasoning: garlic powder, oregano, and salt keep the onion flavor at the center.
- Easy casserole-style method: everything is layered in a 9×13-inch dish and baked until bubbling.
Ingredient Notes
Vidalia onions are especially good here because they are naturally sweet and mild. Slice them into even ¼-inch rounds, then separate the rings so they spread throughout the baking dish instead of staying in thick stacks.
Butter melts down through the onions as they bake, adding richness. Garlic powder and oregano bring a simple savory seasoning without making the dish too busy.
The combination of Italian-blend cheese, cheddar, and Parmesan gives you both melt and flavor. Spreading the cheeses evenly keeps the top from browning in only one area.
Tips for the Best Baked Onions
- Slice the onions evenly so they soften at the same rate.
- Separate the rings before placing them in the baking dish.
- Distribute the butter slices across the entire pan instead of concentrating them in the center.
- Spread the cheese from edge to edge for even browning.
- Bake until the cheese is bubbling and browned and the onions underneath are tender.
What to Serve with Tennessee Onions
This cheesy onion side works well with steak, pork chops, roast chicken, meatloaf, burgers, or grilled meats. For another onion-forward side, try Amish Onion Fritters. You can also browse more easy side dishes or cheesy recipes.
Make Ahead and Storage
You can slice the onions and shred the cheese ahead of time, then assemble the casserole closer to baking. Refrigerate leftovers in a covered container and reheat until hot and the cheese is melted again.
Frequently Asked Questions
Do I need Vidalia onions?
Vidalia onions give this recipe its signature mild sweetness. Another sweet onion can work, but the flavor may be slightly different.
Why are my onions still firm?
The slices may be too thick or the pan may need more baking time. Even ¼-inch rounds soften more consistently.
Ingredients
- 3 to 4 sweet Vidalia onions
- 4 tablespoons butter
- 1 teaspoon salt
- 1 teaspoon garlic powder
- ½ teaspoon oregano
- 1 cup shredded Italian-blend cheese
- 1 cup shredded cheddar cheese
- ½ cup shredded Parmesan cheese
How To Make Tennessee Onions
- Preheat the oven to 350°F.
- Spray a 9×13-inch baking dish with nonstick cooking spray.
- Slice the onions into ¼-inch rounds and separate the rings.
- Spread the onion rings evenly in the baking dish.
- Season with the garlic powder, salt, and oregano.
- Slice the butter into 8 pieces and distribute them evenly over the onions.
- Sprinkle the Italian-blend cheese and cheddar evenly over the top.
- Finish with the Parmesan cheese.
- Bake for 35 to 40 minutes, or until the onions are tender and the cheese is bubbling and browned.
- Serve warm.