Sweet Onion Casserole is a creamy baked side dish made with sweet onions, basmati rice, half-and-half, butter, and Swiss cheese. The onions soften without browning, the rice finishes cooking in the casserole, and the cheese forms a lightly golden top.
This is a good choice for holidays, potlucks, or family dinners when you want something different from potatoes or macaroni and cheese. The onions are the main ingredient, but the rice gives the casserole structure and makes it easier to serve.
Why This Sweet Onion Casserole Works
Cooking the onions only until translucent keeps their flavor sweet and mild instead of deeply caramelized. Half-cooking the rice before baking lets it finish absorbing moisture from the cream and onions in the oven.
Swiss cheese adds a nutty, savory flavor that balances the sweetness of the onions. Most of it is mixed into the casserole, with the remaining cheese reserved for the top.
For more easy sides, browse our Side Dishes and Casseroles.
Ingredient Notes
Sweet onions: Three pounds may look like a lot, but they cook down considerably. Keep the heat moderate so they soften without taking on too much color.
Basmati rice: The rice is only partially cooked before baking. That lets it finish in the creamy onion mixture instead of becoming mushy.
Half-and-half: One cup adds richness without making the dish as heavy as a full cream sauce.
Swiss cheese: Two cups are divided between the filling and topping.
Ingredients
- 3/4 cup uncooked basmati rice
- 5 cups water
- 1/4 cup butter
- 3 pounds sweet onions, coarsely chopped
- 1 cup half-and-half cream
- 1 1/2 teaspoons salt
- 2 cups shredded Swiss cheese, divided
How to Make Sweet Onion Casserole
- Preheat the oven to 350°F and butter a 2-quart baking dish.
- Bring the water to a boil in a large saucepan. Add the rice, reduce the heat to low, and simmer for about 5 minutes, until only partially cooked. Drain and set aside.
- Melt the butter in a large skillet over medium heat. Add the onions and cook for about 8 minutes, stirring often, until translucent but not browned.
- Stir the partially cooked rice into the onions.
- Add the half-and-half, salt, and 1 3/4 cups of the Swiss cheese. Stir until evenly combined.
- Transfer the mixture to the prepared baking dish and sprinkle the remaining 1/4 cup Swiss cheese over the top.
- Bake uncovered for about 1 hour, until the rice is tender and the top is lightly browned.
Tips for the Best Texture
Do not brown the onions heavily. The goal is soft, sweet onions rather than caramelized onions.
Drain the rice well. Extra cooking water can make the casserole looser than intended.
Check the rice before serving. The casserole is ready when the grains are tender and the center is set.
Storage and Reheating
Store leftovers covered in the refrigerator for up to 3 to 4 days. Reheat individual portions in the microwave or cover and warm in the oven until hot.
Frequently Asked Questions
Can I use another rice?
Another long-grain white rice may work, but the cooking time can vary. The published recipe is built around basmati rice.
What should I serve with onion casserole?
It pairs well with roast chicken, beef, pork, ham, or a holiday meal where you want a creamy side that is not potato-based.
