# Ingredients:
→ 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 tbsp unsalted butter
07 - 2 tbsp all-purpose flour
→ Seasonings
08 - 1 tsp salt
09 - 1/2 tsp black pepper
10 - 1/2 tsp garlic powder
11 - 1/4 tsp paprika
# Instructions:
01 - Preheat oven to 375°F. Grease a 9x13-inch baking dish with butter or cooking spray.
02 - Melt butter in a medium saucepan over medium heat. Add flour and whisk continuously for 1 minute to form a roux.
03 - Slowly pour milk into the roux while whisking constantly to prevent lumps. Cook for 3-4 minutes until the sauce thickens slightly.
04 - Remove from heat and stir in salt, pepper, garlic powder, and half of the cheddar and mozzarella cheese until completely melted and smooth.
05 - Arrange half the sliced potatoes in the prepared baking dish. Top with half the onion slices followed by half the cheese sauce. Repeat layers with remaining potatoes, onions, and cheese sauce.
06 - Sprinkle remaining shredded cheeses and paprika evenly over the top layer.
07 - Cover baking dish tightly with aluminum foil and bake for 40 minutes at 375°F.
08 - Remove 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.
