Scalloped Potatoes and Onions

This Scalloped Potatoes and Onions recipe turns everyday ingredients into a rich, satisfying comfort food. Thin slices of russet potatoes are layered with tender sautéed onions and covered in a smooth homemade cheddar cream sauce before baking until the potatoes are perfectly tender and the top is golden and bubbly. It’s a classic side dish that pairs beautifully with roasted meats, grilled chicken, or a simple green salad.

Ingredients

Ingredient	Quantity
Russet potatoes, peeled and thinly sliced	4 large
Medium onions, thinly sliced	2
Sharp cheddar cheese, shredded	2 cups
Unsalted butter, divided	4 tablespoons
All-purpose flour	1/4 cup
Whole milk	2 cups
Salt	1 teaspoon
Black pepper	1/2 teaspoon
Garlic powder (optional)	1/2 teaspoon
Fresh thyme or rosemary, chopped (optional)	1 tablespoon

Instructions

Step 1: Prepare the Oven

Preheat the oven to 350°F (175°C). Lightly grease a 9×13-inch baking dish with butter or nonstick cooking spray.

Step 2: Cook the Onions

In a large skillet, melt 2 tablespoons of butter over medium heat. Add the sliced onions and cook for 10–15 minutes, stirring occasionally, until they are soft, lightly caramelized, and golden.

Step 3: Make the Cheese Sauce

Add the remaining 2 tablespoons of butter to the skillet. Once melted, stir in the flour and cook for 1 minute, stirring constantly. Slowly whisk in the milk until smooth. Simmer over medium-low heat for 5–7 minutes, stirring often, until the sauce thickens.

Step 4: Season the Sauce

Mix in the salt, black pepper, and garlic powder, if using. Remove the skillet from the heat and taste, adjusting the seasoning if desired.

Step 5: Assemble the Casserole

Arrange half of the sliced potatoes in an even layer in the prepared baking dish. Top with half of the cooked onions, 1 cup of the shredded cheddar cheese, and half of the cream sauce. Repeat with the remaining potatoes, onions, cheese, and sauce.

Step 6: Bake Covered

Cover the baking dish tightly with aluminum foil. Bake for 45 minutes, allowing the potatoes to become tender.

Step 7: Brown the Top

Remove the foil and continue baking for 15–20 minutes, or until the cheese is bubbling and golden brown and the potatoes are easily pierced with a fork.

Step 8: Let It Rest

Remove the casserole from the oven and let it rest for 10–15 minutes before serving. This allows the sauce to thicken slightly, making it easier to serve neat portions.

Tip

Allowing the casserole to rest before serving is an important step. As it cools slightly, the creamy sauce sets and thickens, helping each serving hold together while keeping the potatoes rich, tender, and flavorful.