Buttery Southern Onion Bake
If you’ve never tried Tennessee Onions, get ready for a true Southern comfort food favorite. This easy onion casserole recipe transforms sweet onions into a buttery, cheesy, melt-in-your-mouth side dish that pairs perfectly with grilled meats, roast dinners, or holiday spreads. With simple ingredients and minimal prep, it’s ideal for busy weeknights but impressive enough for gatherings. As the onions bake, they turn tender and slightly sweet, soaking up rich butter and gooey cheese for that irresistible golden crust. It’s cozy, crowd-pleasing, and dangerously easy to love!
⏱️ Time Breakdown
- Prep Time: 10 minutes
- Cook Time: 35–40 minutes
- Total Time: 45–50 minutes
- Servings: 6
📝 Ingredients List
- 4 large sweet onions (Vidalia preferred), sliced into ¼-inch rings
- 6 tablespoons unsalted butter, thinly sliced
- 1 cup shredded sharp cheddar cheese
- 1 cup shredded mozzarella cheese
- ½ cup shredded Parmesan cheese
- ½ teaspoon garlic powder
- ½ teaspoon salt
- ½ teaspoon black pepper
- ½ teaspoon dried oregano
✨ Kitchen Tools You’ll Need
This recipe doesn’t require fancy gadgets, just a few reliable kitchen basics to keep everything simple and stress-free.
- Sharp knife
- Cutting board
- 9×13-inch baking dish
- Measuring spoons
- Aluminum foil
- Oven mitts
👩🍳 Step-by-Step Beginner-Friendly Instructions
Step 1: Preheat the Oven
Preheat your oven to 350°F (175°C). Lightly grease your baking dish.
Step 2: Layer the Onions
Arrange the sliced onion rings evenly in the baking dish. Separate them slightly so they cook evenly.
Step 3: Add Butter & Seasoning
Distribute the sliced butter evenly over the onions. Sprinkle garlic powder, salt, pepper, and oregano across the top.
Step 4: Add the Cheese
Sprinkle cheddar, mozzarella, and Parmesan evenly over the onions. Make sure the top is well covered for that golden crust 🧀
Step 5: Cover & Bake
Cover the dish with foil and bake for 25 minutes.
Step 6: Uncover & Finish Baking
Remove the foil and bake an additional 10–15 minutes, until the cheese is melted, bubbly, and lightly golden. The onions should be fork-tender and fragrant 😊
Let rest for 5 minutes before serving so the cheese sets slightly.
💡 Pro Tips
- Best Onions: Sweet onions like Vidalia work best because they soften beautifully and develop natural sweetness.
- Storage: Keep leftovers refrigerated in an airtight container for up to 3 days.
- Reheating Tip: Reheat in the oven at 325°F to maintain the cheesy texture.
- Extra Flavor: Add a dash of smoked paprika or a sprinkle of fresh thyme before serving.
🔄 Variations
- Add Crunch: Top with crushed buttery crackers during the last 10 minutes of baking.
- Spicy Version: Add sliced jalapeños for heat.
- Herb Upgrade: Mix fresh chopped parsley into the cheese before baking.
- Creamy Twist: Drizzle ¼ cup heavy cream over the onions before baking for extra richness.
❓ FAQ
Do I need to sauté the onions first?
No, Tennessee Onions are traditionally baked raw. The slow bake makes them tender and sweet.
Can I make this ahead of time?
Yes! Assemble the dish, cover, and refrigerate up to 24 hours before baking.
What does this pair well with?
It’s perfect alongside grilled steak, roast chicken, or holiday ham-style beef roasts.
Can I freeze it?
It’s best fresh, but you can freeze after baking. Thaw overnight in the refrigerator before reheating.