# Components:
→ 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
# Directions:
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 smooth paste forms.
03 - Slowly pour in milk while whisking constantly to prevent lumps from forming. Continue cooking until sauce thickens slightly, approximately 3 to 4 minutes.
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 - Arrange half the potato slices in the prepared baking dish. Top with half the onion slices followed by half the cheese sauce. Repeat layering with remaining potatoes, onions, and cheese sauce.
06 - Sprinkle remaining shredded cheeses and paprika evenly over the top layer.
07 - Cover baking dish with aluminum foil and bake for 40 minutes at 375°F.
08 - Remove foil and continue baking for 25 to 30 minutes until potatoes are tender and the top is golden brown.
09 - Remove from oven and let rest for 10 minutes before serving to allow flavors to settle.