# Ingredient List:
→ Vegetables
01 - 2.5 lbs russet or Yukon Gold potatoes, peeled and thinly sliced
02 - 1 small yellow onion, thinly sliced
→ Dairy
03 - 2 cups whole milk
04 - 1 cup heavy cream
05 - 2 cups sharp cheddar cheese, shredded
06 - 1 cup Gruyère or Monterey Jack cheese, shredded
07 - 4 tablespoons unsalted butter
→ Pantry & Spices
08 - 3 tablespoons all-purpose flour
09 - 1 teaspoon garlic powder
10 - 1 teaspoon salt, plus more to taste
11 - ½ teaspoon ground black pepper
12 - ¼ teaspoon smoked paprika
13 - Chopped fresh chives or parsley, for garnish (optional)
# Steps:
01 - Preheat the oven to 375°F. Grease a 9x13-inch baking dish with butter.
02 - In a medium saucepan over medium heat, melt the butter. Whisk in flour continuously for 1 to 2 minutes until bubbly without browning.
03 - Gradually whisk in milk and cream. Stir constantly until thickened, about 3 to 5 minutes. Remove from heat and stir in garlic powder, salt, pepper, and smoked paprika.
04 - Add 1½ cups cheddar and ½ cup Gruyère cheese to the sauce. Stir until cheeses melt and sauce is smooth.
05 - Arrange half of the potato slices in an even layer in the baking dish. Top evenly with half of the sliced onions.
06 - Pour half of the cheese sauce over potatoes and onions. Repeat with remaining potatoes and onions, then pour the remaining cheese sauce on top.
07 - Sprinkle the remaining cheddar and Gruyère cheeses evenly across the top.
08 - Cover the dish tightly with foil and bake for 45 minutes.
09 - Remove the foil and bake an additional 25 to 30 minutes until potatoes are tender and the surface is golden and bubbling.
10 - Let rest for 10 minutes before garnishing with chives or parsley and serving.
