# 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
# Directions:
01 - Preheat oven to 375°F. Grease a 9x13-inch baking dish and set aside.
02 - Melt butter in a medium saucepan over medium heat. Add flour and whisk continuously for 1 minute until a smooth paste forms.
03 - Slowly pour milk into the roux while whisking constantly to prevent lumps. Continue cooking until sauce thickens slightly, approximately 3 to 4 minutes.
04 - Remove from heat and stir in salt, black pepper, garlic powder, and half of the cheddar and mozzarella cheeses until completely melted and smooth.
05 - Arrange half of the sliced potatoes 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 cheddar and mozzarella cheeses evenly over the top layer. Dust with paprika.
07 - Cover baking dish with aluminum foil and bake for 40 minutes in the preheated 375°F oven.
08 - Remove foil and continue baking for an additional 25 to 30 minutes until potatoes are tender and the top achieves a golden brown color.
09 - Allow the dish to rest at room temperature for 10 minutes before portioning and serving.