Easy & Flavorful Tennessee Onions: A Perfect Vegetable Side Dish (2024)

Tennessee onions are a simple yet delicious side dish that combines sweet Vidalia onions with herbs and melted cheese! Enjoy them on the side or use them as a topping for burgers or hot dogs! This will quickly become your new favorite way to prepare onions!

Best Tennessee Onions Casserole

Sauteed, caramelized, roasted, grilled- I love onions in every way, shape, and form! They are used in so many savory dishes because they easily add a ton of extra flavor!

This simple onion casserole gives you a whole new way to enjoy this delicious vegetable! Sliced sweet onions are perfectly seasoned and smothered in cheese and butter- what more could you possibly want?

🥘 Ingredients

The onions are easily the star of this recipe, so make sure you use your favorite sweet variety. You'll also want some fantastic cheese for melting!

• Sweet Onions - 2½ pounds of sweet onions, such as Vidalia or Walla Walla onions.
• Seasonings - 1 teaspoon of garlic powder, ½ teaspoon of oregano (or use an oregano substitute), ¼ teaspoon of dry mustard powder (or check out these substitutes), ¼ teaspoon of salt, ¼ teaspoon of pepper, and an optional pinch of cayenne pepper if you would like some extra heat.
• Butter - 4 tablespoons of salted butter cut into pats that are about ½ tablespoon each.
• Cheddar - 1 cup of shredded sharp cheddar cheese.
• Mozzarella - 1 cup of shredded mozzarella cheese. Alternatively, you could use Gouda or Monterey Jack.
• Parmesan - ½ cup of shredded Parmesan cheese.

*Be sure to see the free printable recipe card below for ingredients, exact amounts & instructions with tips!*

🔪 How To Make Tennessee Onions

With how simple this casserole is to prepare, you're going to be blown away by how tasty it is! All you will need to get started is a knife and cutting board (or a mandoline), some measuring spoons, a cheese grater, and a 9x13 baking dish.

This recipe will make 8 servings of sweet and cheesy onions!

Step 1: Preheat. Preheat your oven to 350°F (175°C/Gas Mark 4) and butter a 9x13 baking dish.

Step 2: Prepare onions. Slice2½ pounds (1.13 kilograms) of yellow onionsto be approximately ¼-inch thick slices, then spread the onion rings in your prepared baking dish.

Step 3: Season. Season with1 teaspoon (3 grams) of garlic powder,½ teaspoon (1 gram) of oregano,¼ teaspoon (0.5 grams) of dry mustard powder,¼ teaspoon (1.5 grams) of both salt & pepper and the optional1 pinch of cayenne pepper.

Step 4: Add butter. Place the sliced pats of4 tablespoons (56 grams) of butterover the seasoned onion rings in the dish, spreading them so that they’re evenly placed.

Step 5: Layer. Layer the1 cup (113 grams) of cheddar cheese,1 cup (112 grams) of mozzarella cheese, and½ cup (50 grams) of Parmesan cheesein even layers over the onions. Push the cheese to the edges of the dish.

Step 6: Bake. Bake at 350°F (175°C/Gas Mark 4) for 40-45 minutes or until the cheese is melted and bubbly and the onions are tender. If desired, you can broil for a couple of minutes to brown the top of the onion casserole.

Step 7: Serve. Remove from the oven and serve immediately.

🌭 What To Serve With Tennessee Onions

These onions could easily be considered a side dish or even a condiment! They make a fantastic potluck side dish to be paired with crack chicken or pinwheel sandwiches.

As a condiment, load them up atop some grilled chicken quarters, grilled skirt steak, ribeye steak, burgers, or grilled brats! Enjoy!

💭 Tips & Notes

• 2½pounds of onions is approximately 3 large onions or 4 medium-sized onions.
• You can swap the butter for 1 cup of mayo over the sliced onions for a rich and tasty alternative. Chop the onions and serve this version as a hot dip for appetizers.
• Separate the onion rings from each other (don't leave them nested) so that they cook evenly.
• Serve with steak, burgers, meatloaf, or any hearty protein over hot dogs or sausages.

🥄 Make Ahead Options

This casserole is already so easy to prepare, but here are a few other ways you can save yourself some time!

First, you can slice your onions and shred your cheese in advance. Store them both separately in a sealed container for a day or two until you are ready to assemble the casserole and bake.

Second, if needed, you can make the casserole completely the day before and keep it in the fridge. When ready, you can reheat it in the oven.

🥡 Storing & Reheating

Allow your casserole to cool to room temperature, and then store it in a sealed, airtight container in the refrigerator for up to 4 days.

Reheating

Reheat your Tennessee onions by covering the dish with foil and baking in the oven at350°F (175°C/Gas Mark 4) until heated through.Of course, if you are only reheating small amounts at a time, you could use the microwave.

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