Tennessee Onions (Cheesy Baked Onion Casserole)
1 h
|
easy
Recipe by Eunice
Introduction
Meet Tennessee onions, the Southern potluck favorite where sweet Vidalia rings bake in butter, garlic, and smoked paprika under a three-cheese blanket until bubbling, golden, and ridiculously good.
Perfect with BBQ, burgers, steak night, or holiday spreads, this low-effort casserole delivers sweet-savory depth, cheesy pull, and those crispy edges everyone fights for.
Ingredients (6 servings)
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Ingredients
- 3 large Vidalia onions, peeled, cut into ½-inch thick rings Vidalia onions 0.75 lb large
- 4 Tbsp unsalted butter, melted unsalted butter 2 oz
- 1 tsp granulated vegetable bouillon granulated vegetable bouillon 0.14 oz
- ½ tsp salt salt
- ¼ tsp freshly ground black pepper black peppercorns (for freshly ground black pepper)
- 1 tsp garlic powder garlic powder 0.1 oz
- ½ tsp smoked paprika smoked paprika 0.04 oz
- 1 tsp fresh thyme fresh thyme 0.04 oz
- 1½ cups shredded sharp cheddar cheese shredded sharp cheddar cheese 6 oz
- 1 cup shredded mozzarella cheese shredded mozzarella cheese 3.03 oz
- ½ cup grated Parmesan cheese grated Parmesan cheese 1.43 oz
How to Make Tennessee Onions (Cheesy Baked Onion Casserole)
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Preheat and prep the dish
Heat the oven to 375 F and set a rack in the center.
Brush a 9x13 inch baking dish with a little of the melted butter to lightly coat the bottom.
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Season the butter
Whisk the vegetable bouillon powder, salt, black pepper, garlic powder, smoked paprika, and thyme into the remaining melted butter until fully dissolved and fragrant.
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Arrange the onions
Separate the onion slices into rings and shingle them in the dish in an even layer without mounding so they soften evenly and do not steam into mush.
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Coat and start the bake
Drizzle the seasoned butter evenly over the onions, tossing gently with your hands to make sure every ring is glossed, then spread back into a flat layer.
Cover tightly with foil and bake for 25 minutes to let the onions soften and release some juices.
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Add the cheeses
Uncover, drain off a few tablespoons of excess liquid if the dish looks soupy, then evenly scatter the cheddar and mozzarella over the onions and finish with a shower of Parmesan.
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Finish baking
Return to the oven uncovered and bake 18 to 20 minutes until the cheeses are fully melted, bubbling at the edges, and lightly golden.
If you want deeper color, broil for 1 to 2 minutes, watching closely like a hawk.
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Rest and serve
Let the casserole rest 10 minutes so the cheese sets and the flavors round out, then sprinkle on a few fresh thyme leaves if you like and serve hot.
Substitutions
- Vidalia onions -> other sweet onions
- Swap Vidalia with Walla Walla or Maui onions for the same mellow sweetness and tender texture, keeping the casserole lush instead of sharp.
- Sharp cheddar -> Gruyere
- Use Gruyere in place of cheddar for a silkier melt and a nutty, savory depth that plays beautifully with the thyme and paprika.
- Unsalted butter -> ghee
- Replace butter with ghee for a richer, toasted flavor and better browning without any risk of the milk solids scorching.
Tips
- Uniform 1/2 inch rings matter
- Even thickness guarantees the onions soften at the same rate, so you get jammy texture without raw crunch or stringy bits.
- Two-stage bake for control
- Covering first steams the onions gently, then uncovering lets moisture evaporate and concentrates flavor before the cheese goes on.
- Cheese layering strategy
- Mix cheddar and mozzarella for stretch and punch, then finish with Parmesan on top to brown and form a savory crust.
- Mind the liquid
- If the onions release a lot of juice, spoon off a little before adding cheese so the top crisps and the casserole does not feel watery.
- Use the right pan
- A wide 9x13 dish gives you a shallow layer that reduces excess moisture and promotes caramelized edges instead of a steamy pile.
- Resting is not optional
- Ten minutes off heat lets the bubbling calm and the cheese set, so scoops hold together and flavors taste fuller.
Nutrition Facts *
| Energy | 313 | kcal |
|---|---|---|
| Protein | 15 | g |
| Total Fat | 23 | g |
| Carbohydrates | 9 | g |
| Dietary Fiber | 1 | g |
* Approximate, per serving.
Data source: USDA FoodData Central.
FAQ
- How do I prevent the casserole from turning watery?
- Bake covered just until the onions slump, then uncover to drive off moisture, and ladle off a bit of liquid before adding the cheese if needed.
- Can I make this ahead?
- Bake covered for 25 minutes, cool, then refrigerate; when ready, top with cheeses and bake uncovered until bubbly so the cheese stays fresh and melty.
- What if my onions are sharper than Vidalia?
- Soak rings in ice water for 10 minutes, drain and pat dry to mellow the bite without losing texture.
- Can I use red or yellow storage onions?
- Yes, but red onions can tint the dish and taste stronger, while standard yellow onions will be a bit more pungent and less sweet.
- How do I avoid a greasy top?
- Stick to the listed butter amount, use part-skim mozzarella if you like, and give the dish a short uncovered bake to let excess fat emulsify and render off the surface.
Serving Suggestions
This is outrageous next to grilled steak or roasted chicken, but it also slaps spooned over a baked potato or a smash burger for a caramelized-onion-cheese moment.
If you want a little swagger, add a pinch of red pepper flakes with the paprika or finish with a drizzle of hot honey to contrast the sweet onions and salty cheese.
More pairings:
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