# What you need:
→ 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 constantly for 1 minute to form a roux.
03 - Slowly pour in milk while whisking constantly to prevent lumps. Cook for 3-4 minutes until mixture thickens slightly.
04 - Remove from heat. Stir in salt, pepper, garlic powder, and half of the cheddar and mozzarella cheeses until melted and smooth.
05 - Spread half the sliced potatoes in prepared baking dish. Top with half the onion slices and half the cheese sauce. Repeat layering with remaining potatoes, onions, and sauce.
06 - Sprinkle remaining shredded cheeses and paprika over the top layer.
07 - Cover baking dish with aluminum foil and bake for 40 minutes.
08 - Remove foil and bake an additional 25-30 minutes until potatoes are tender and top is golden brown.
09 - Remove from oven and let rest for 10 minutes before serving.