# Ingredient List:
→ Vegetables
01 - 2 lbs Yukon Gold or Russet potatoes, peeled and thinly sliced
02 - 1 medium yellow onion, thinly sliced
→ Dairy
03 - 2 cups shredded sharp cheddar cheese
04 - 1 cup shredded mozzarella cheese
05 - 2 cups whole milk
06 - 2 tablespoons unsalted butter
07 - 2 tablespoons all-purpose flour
→ Seasonings
08 - 1 teaspoon salt
09 - 1/2 teaspoon black pepper
10 - 1/2 teaspoon garlic powder
11 - 1/4 teaspoon paprika
# How-To Steps:
01 - Preheat oven to 375°F. Grease a 9x13-inch baking dish with butter or cooking spray.
02 - Melt 2 tablespoons butter in a medium saucepan over medium heat. Add flour and whisk continuously for 1 minute until a roux forms.
03 - Slowly pour in 2 cups milk while whisking constantly to prevent lumps. Continue cooking for 3-4 minutes until the sauce thickens slightly.
04 - Remove saucepan from heat. Stir in salt, black pepper, garlic powder, and half of the cheddar and mozzarella cheeses until completely melted and smooth.
05 - Distribute half the sliced potatoes evenly in the prepared baking dish. Top with half the onion slices, then pour half the cheese sauce over the layer. Repeat with remaining potatoes, onions, and cheese sauce.
06 - Sprinkle the remaining shredded cheddar and mozzarella cheeses over the top layer. Finish with paprika for color and flavor.
07 - Cover the baking dish tightly with aluminum foil. Bake for 40 minutes in the preheated 375°F oven.
08 - Remove aluminum foil and continue baking for 25-30 minutes until potatoes are tender and the top is golden brown.
09 - Remove from oven and allow to rest for 10 minutes before serving. This resting period helps the layers set and improves texture.