Want to know what was ‘pon Rocky Top? Tennessee Onions — a simple, savory Vidalia onion casserole that’s cheesy, comforting, and easy to make. This Southern-style Tennessee Onions Casserole highlights sweet Vidalia (or other sweet) onions baked with butter, garlic, and a trio of cheeses. It’s a classic side dish or vegetarian option that’s been on my table for decades — give it a try!
This baked Vidalia onion recipe is built around sweet onion rings layered in a baking dish, seasoned with garlic and pepper, dotted with butter, and covered in shredded cheddar, mozzarella, and grated Parmesan. The result is tender, slightly caramelized onions with a golden, bubbly cheese topping — perfect for summer when sweet onions are in season or any time you can find good sweet onions.
Why This Baked Vidalia Onion Recipe Works
- Uses few, familiar ingredients: Vidalia or other sweet onions, butter, garlic salt, pepper, and three cheeses.
- Simple preparation — slice, layer, season, top with cheese, and bake.
- Deliciously versatile: serve as a side, topper for burgers and steaks, or a vegetarian option at gatherings.
Frequently Asked Questions (FAQs)
Is this recipe vegetarian?
Yes. Tennessee Onions is an excellent vegetarian side or sandwich topping when prepared without added meat. Use vegetarian-friendly cheeses if desired.
What are Tennessee Onions?
“Tennessee Onions” is a name for this comforting baked sweet onion casserole. Though Vidalia onions originate in Georgia, the name captures the Southern flavors — buttery, garlicky, and rich with melted cheese.
Are Vidalia onions the same as sweet onions?
Vidalia onions are a type of sweet onion. If Vidalias aren’t available, substitute other sweet varieties like Texas sweets or cipollini onions.
How should I store Vidalia onions?
Store whole sweet onions in a cool, dry, well-ventilated, dark spot. Once prepared, Tennessee Onions keep well in an airtight container in the refrigerator for up to five days.
When are Vidalia onions in season?
Vidalia onions are typically in season in late spring through summer. Other sweet onion varieties may be available year-round.
Tips for Perfect Tennessee Onions
- Slice onions evenly (about 1/4 to 1/2 inch) and separate into rings for uniform cooking.
- Use the best-quality cheese you can — it makes a noticeable difference in flavor.
- Check for added salt before seasoning: garlic salt and cheeses add saltiness.
- Bake until onions are soft and cheese is bubbly and beginning to brown — about 30–40 minutes depending on slice thickness.
- Garnish with fresh herbs like oregano, chives, or thyme just before serving.
- Serve as a side at cookouts, over hamburgers, with steak, or as a flavorful addition to vegetarian plates.
Serving Suggestions
Tennessee Onions pair beautifully with grilled meats, burgers, potato salad, or a fresh green salad. They also make a great savory topping for vegetarian burgers or a hearty sandwich.
Here’s How You Do It
STEP 1. Slice the onions into 1/4 to 1/2 inch rounds and separate the rings.
STEP 2. Layer the rings in a prepared baking dish, season with garlic salt and pepper, and dot with pats of butter.
STEP 3. Sprinkle with shredded cheddar and mozzarella, then top with grated Parmesan.
STEP 4. Bake until the onions are tender and the cheese is bubbling and lightly browned. Let cool a few minutes, garnish with fresh herbs, and serve.
Can You Give Me a Hand?
If you enjoy this recipe, please leave a five-star comment and share how you served it. Reader feedback helps others discover this easy, flavorful Vidalia onion casserole.
Tennessee Onions
Ingredients
- 2–3 whole Vidalia onions (or any sweet onion)
- 4 tablespoons unsalted butter
- 1 teaspoon garlic salt
- 1/2 teaspoon black pepper
- 1 cup shredded sharp cheddar cheese (higher quality for better flavor)
- 1 cup shredded mozzarella cheese
- 1/2 cup grated Parmesan cheese
- Fresh oregano, chives, or thyme for garnish
Instructions
- Preheat oven to 350°F (175°C). Prepare a 9×9 or 9×13 baking dish with non-stick cooking spray.
- Slice Vidalia onions into 1/4 to 1/2 inch rounds and separate into rings.
- Arrange the rings evenly in the prepared baking dish.
- Sprinkle the rings with garlic salt (about 1 teaspoon) and black pepper (about 1/2 teaspoon).
- Cut the butter into pats and distribute them across the onions.
- Top with shredded cheddar and mozzarella, then sprinkle the Parmesan over the top.
- Bake uncovered at 350°F for about 30 minutes, or until the onions are tender and the cheese is bubbly and beginning to brown.
- Remove from the oven, let rest a few minutes, garnish with fresh herbs, and serve.
Notes
- Serve over hamburgers, with steak, as a side at cookouts, or as a vegetarian burger option.
- Slicing the onions evenly ensures consistent cooking; thinner slices will finish sooner.
- Vidalia onions are preferred, but Texas Sweets or other sweet onions work well.
- These bake into soft, flavorful onions topped with a cheesy crust — not a custard filling.
- Store leftovers in an airtight container in the fridge up to five days.
Nutrition
A VERSE TO SHARE
The Bible’s account of manna reminds me to be grateful for simple blessings — even a humble dish like Tennessee Onions that brings comfort and flavor. Thankful for good food and the people we share it with.
John 6:31
Our fathers ate the manna in the wilderness; as it is written, ‘He gave them bread from heaven to eat.’
***This post has been updated with new information***