A Southern Classic That Deserves the Spotlight
When you think of Southern comfort food, classics like mac and cheese, fried chicken, or cornbread might come to mind. But there’s one hidden gem that deserves just as much attention—Tennessee Onions. This rich, cheesy, buttery onion casserole is the definition of comfort in every bite. With layers of sliced sweet onions smothered in cheese and baked until golden and bubbly, it’s a simple side dish with bold Southern flavor.
Whether served with steak, barbecue, or roasted chicken, Tennessee Onions will turn your everyday dinner into a memorable meal. If you’re looking to elevate your side dish game, this one is a must-try.
What Are Tennessee Onions?
Tennessee Onions are not your average onion side dish. They're made by layering thick-cut sweet onions in a baking dish, seasoning them generously, and covering them with a rich blend of shredded cheeses. Butter is added for extra flavor, and the entire dish is baked until golden and bubbling.
The result? A deliciously savory, cheesy dish with just a hint of sweetness from the onions. The edges get slightly crispy, the center stays soft and melty, and the taste is unforgettable.
Ingredients You’ll Need
To create the perfect Tennessee Onion casserole, gather these simple ingredients:
- 3–4 large sweet onions (Vidalia or Walla Walla preferred)
- 4 tablespoons unsalted butter, sliced into small cubes
- 1 teaspoon garlic powder
- 1 teaspoon onion powder
- ½ teaspoon kosher salt
- ½ teaspoon black pepper
- 1½ cups shredded mozzarella cheese
- 1 cup shredded sharp cheddar cheese
- ½ cup freshly grated parmesan cheese
- Fresh parsley or thyme for garnish (optional)
These pantry staples combine to create a flavor-packed dish with minimal effort.
Step-by-Step Instructions
1. Preheat the Oven
Start by preheating your oven to 375°F (190°C). Grease a 9x13-inch baking dish lightly with butter or cooking spray.
2. Slice the Onions
Peel the onions and cut them into thick slices or rings. Keeping them about ½ inch thick ensures they won’t turn mushy during baking.
3. Layer the Onions
Arrange the onion slices evenly across the baking dish. Overlap slightly to ensure even cooking and full coverage.
4. Season Generously
Sprinkle garlic powder, onion powder, salt, and pepper over the onion slices. Make sure each layer is well seasoned to deepen the flavor.
5. Add Butter Cubes
Dot the surface with sliced butter. The butter will melt into the onions, adding richness and helping them caramelize while baking.
6. Top with Cheese
Layer the shredded mozzarella, cheddar, and parmesan over the onions. Use a generous hand—the more cheese, the better the flavor and texture.
7. Bake Until Golden
Place the baking dish in the oven and bake for 30 to 35 minutes or until the cheese is melted, bubbly, and slightly browned on top.
8. Garnish and Serve
Remove from the oven and let it rest for five minutes. Garnish with freshly chopped parsley or thyme for color and aroma. Serve hot.
Flavor Variations to Try
Though the traditional recipe is unbeatable, you can always experiment with variations:
- Add cooked bacon bits for a smoky kick.
- Sprinkle with crushed Ritz crackers or seasoned breadcrumbs before baking for added crunch.
- Use a blend of cheeses like pepper jack, Monterey Jack, or Gruyère for different flavor profiles.
- Mix in a splash of heavy cream or sour cream if you want a creamier casserole texture.
- Add thinly sliced jalapeños if you prefer a little heat.
Tips for the Best Tennessee Onions
- Use sweet onions – Vidalia or Walla Walla onions are ideal for this dish. Their natural sweetness enhances the overall flavor.
- Don’t skimp on seasoning. Onions can handle a good amount of salt and spices.
- Shred your own cheese. Pre-shredded cheese contains anti-caking agents that prevent it from melting smoothly.
- Bake uncovered. This allows the top layer of cheese to brown nicely.
- Let it rest before serving. It helps the cheese set and makes scooping easier.
Why Tennessee Onions Are Perfect for Any Occasion
Tennessee Onions shine as a versatile side. They’re easy enough for weeknight dinners yet impressive enough for holidays. Their rich flavor pairs beautifully with a variety of main courses.
Here are some pairing ideas:
- Grilled Ribeye or T-Bone Steak
- BBQ Ribs or Pulled Pork
- Oven-Roasted Chicken or Turkey
- Baked Ham or Glazed Pork Loin
- Southern Meatloaf or Salisbury Steak
- Holiday Potlucks and Sunday Suppers
How to Make It Ahead of Time
Hosting a big dinner or holiday meal? You can prep Tennessee Onions in advance.
- Assemble the dish completely up to one day ahead.
- Cover and refrigerate until ready to bake.
- Let sit at room temperature for 20–30 minutes before placing in the oven.
- Bake as directed until hot and bubbly.
This makes it an ideal dish for entertaining or meal prepping.
Storing and Reheating Leftovers
Got leftovers? Great! Tennessee Onions taste just as good the next day.
- Refrigerate in an airtight container for up to 4 days.
- Reheat in the oven at 350°F until warmed through, or microwave in 30-second intervals.
- Avoid freezing, as the texture of the onions and cheese may change.
Nutrition Overview (Approximate)
While this dish isn’t exactly light, it’s well worth the indulgence. Here’s a general breakdown per serving:
- Calories: 280–320
- Fat: 22g
- Carbohydrates: 12g
- Protein: 10g
- Fiber: 2g
- Sugar: 5g
You can reduce calories slightly by using reduced-fat cheese and less butter.
Frequently Asked Questions
Can I use yellow onions instead of sweet onions?
Yes, but the taste will be more pungent. Sweet onions provide the best balance of flavor.
Can I add meat to make this a main dish?
Absolutely. Try adding browned sausage, chopped ham, or rotisserie chicken.
Can I make it in a slow cooker?
This recipe is best baked to get that golden cheese crust, but you can layer everything in a slow cooker and cook on low for 4–5 hours.
Why You’ll Love Tennessee Onions
Tennessee Onions are:
- Simple to make with everyday ingredients.
- Deeply flavorful from the cheese, butter, and slow-baked onions.
- Customizable for every taste and occasion.
- Great for meal prep, holidays, or potlucks.
- Comfort food at its finest.
A Final Bite of Southern Comfort
Few side dishes bring the same comfort, nostalgia, and flavor as Tennessee Onions. This humble yet indulgent recipe proves that even the simplest ingredients can come together to create something truly memorable.