Tennessee Onions (Cheesy Baked Onion Casserole)
Thick sweet-onion rings baked tender under a golden blanket of butter and three cheeses
These Tennessee onions are the side dish people talk about — thick rings of sweet onion baked until tender and silky, buried under butter, seasoning and a bubbling three-cheese blanket, just like the close-up in the photo.
Estimated per serving: 190 calories, 6g protein and 6g net carbs. Ready in about 50 minutes.
Bake: 35 min
Why you'll love these Tennessee onions
- Onions turn sweet, tender and silky — not a raw bite anywhere
- Three cheeses for melt, stretch and golden edges
- Just 6g net carbs per serving
- Five minutes of layering, then the oven does the work
- The side that steals steak night, BBQs and Sunday roasts
- That stacked, cheesy-ring look from the photo
Health notes
- Sweet onions: Natural sweetness and prebiotic fibre with no added sugar.
- Real cheese: Protein and satiety; a little goes a long way over a whole dish.
- No breadcrumbs or flour: Nothing starchy hidden in this casserole.
- Olive oil swap: Replace half the butter if you prefer.
- Estimated macros: No nutrition card came with this one, so values are estimated and kept consistent throughout.
Key element — covered first, uncovered to finish
Bake the layered onions covered for the first 20 minutes so they steam tender in their own juices, then uncover to let the cheese bubble and catch golden edges. Uncovered the whole time, the tops scorch before the middle onions soften.
Diabetic-Friendly
Tennessee Onions (Cheesy Baked Onion Casserole)
Servings
8
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- Prep15 min
- Total15 min
- Servings8 servings
- Calories190 kcal
Ingredients
Instructions
- Slice thick rings. Heat the oven to 350°F. Peel the onions and slice them into thick rings, about ½-inch wide, keeping the rings together as rounds — that's the stacked look from the photo.
- Layer the dish. Grease a 9×13-inch (or similar) baking dish. Arrange the onion rounds in slightly overlapping layers, like roof tiles.
- Season and butter. Scatter the garlic powder, Cajun seasoning, salt and pepper evenly over the onions. Dot the butter pieces all over the top so it melts down through the layers.
- Cheese blanket. Cover the onions completely with the cheddar and mozzarella, then shower the Parmesan over the top.
- Bake covered, then uncovered. Cover with foil and bake for 20 minutes. Remove the foil (mind the steam) and bake 12–15 minutes more until the cheese is bubbling with golden, crisp edges. Use oven mitts for the hot dish.
- Rest and serve. Rest for 5–10 minutes so the cheese settles. Scatter with parsley and serve hot with a wide spatula, keeping the pretty ring stacks together.
Notes & Tips
- Sweet onions are the recipe — ordinary onions stay harsh. Look for Vidalia-style.
- Keep the rings whole; separated rings collapse into a tangle.
- Onions release juice as they bake; a little in the dish is normal and delicious.
- For darker, crispier cheese edges, give it 1–2 minutes under a hot grill at the end — watch it closely.
- Serve with a spatula, not a spoon, to keep the stacks intact.
Variations & serving ideas
- Cheese mix: Gruyère and cheddar is a beautiful, deeper-flavoured swap.
- Spicy: Smoked paprika and a pinch of cayenne in the seasoning.
- Extra richness: A few spoonfuls of cream between the layers.
- Crunchy top: Crushed pork rinds scattered over for the last 5 minutes (keeps it low-carb).
- Bacon: Crumbled cooked bacon between the layers and on top.
- French onion style: Gruyère only, thyme, and a splash of stock between the layers.
- BBQ: Sugar-free BBQ seasoning and smoked cheddar.
- Single-serve stacks: Stack rings in a muffin tin for individual portions, 25 minutes total.
Storage
- Refrigerator: Up to 4 days (Covered; the onions get even sweeter as they sit)
- Freezer: Up to 2 months (Texture softens; best used later in soups and omelettes)
- Reheat: — (Covered at 350°F for 12–15 minutes until the cheese bubbles again)
Nutrition Facts
Per serving · makes 8 servings
| Nutrient | Amount per serving |
|---|---|
| Calories | 190 kcal |
| Total fat | 13 g |
| Sodium | 480 mg |
| Total carbohydrate | 8 g |
| Fibre | 2 g |
| Protein | 6 g |
Nutrition values are approximate and vary with brands and portion sizes.
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