Creamy au Gratin Potatoes

Au gratin potatoes made with thinly sliced potatoes and onions baked in a decadently rich and creamy Cheddar cheese sauce until tender and bubbling.

• Preparation Time: 30 mins
• Cooking Time: 1 hr 30 mins
• Total Time: 2 hr
• Calories: 499 Calories

Ingredients

• 3 tablespoons butter
• 2 cups milk
• 3 tablespoons all-purpose flour
• salt and ground black pepper to taste
• 1 medium onion, sliced into rings
• 4 medium russet potatoes, thinly sliced
• 0.5 teaspoon salt
• 1.5 cups shredded Cheddar cheese

Recipe Instructions

Step 1

Bake in the preheated oven until potatoes are tender and sauce is bubbly, about 1 ½ hours.

Step 2

Layer 1/2 of the potatoes in the bottom of the prepared casserole dish; season with salt and pepper.

Step 3

Layer onion slices over top, then top with with remaining potatoes. Season again with salt and pepper.

Step 4

Melt butter in a medium saucepan over medium heat. Gradually whisk in flour and salt and cook, whisking constantly until raw flour flavor has cooked off, about 1 minute.

Step 5

Gradually add milk, about 1/4 cup at a time, whisking well after each addition to incorporate; the gradual addition and whisking of milk will help avoid lumps in your sauce.

Step 6

Cook, whisking constantly, until the mixture has thickened, 3 to 5 minutes.

Step 7

Stir in cheese all at once; continue stirring until melted, 30 to 60 seconds.

Step 8

Pour cheese sauce over the potatoes, and cover the dish with aluminum foil.

Step 9

Gather all ingredients. Preheat the oven to 400 degrees F (200 degrees C). Butter a 2-quart casserole dish.