# What You'll Need:
→ Vegetables
01 - 2.5 pounds 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)
# Method:
01 - Preheat the oven to 375°F. Grease a 9x13-inch baking dish with butter.
02 - Melt butter in a medium saucepan over medium heat. Whisk in flour continuously for 1 to 2 minutes until bubbly but not browned.
03 - Gradually whisk in whole milk and heavy cream. Continue whisking until the mixture thickens, about 3 to 5 minutes.
04 - Stir in garlic powder, salt, black pepper, and smoked paprika. Remove the sauce from heat.
05 - Add 1½ cups sharp cheddar and ½ cup Gruyère cheese to the sauce. Stir until cheeses melt and the sauce is smooth.
06 - Arrange half of the sliced potatoes evenly in the prepared baking dish. Top with half of the sliced onions.
07 - Pour half of the cheese sauce over the potatoes and onions. Layer the remaining potatoes and onions on top, then cover with the remaining cheese sauce.
08 - Evenly sprinkle the remaining sharp cheddar and Gruyère cheeses over the assembled layers.
09 - Cover the dish tightly with aluminum foil and bake for 45 minutes.
10 - Remove the foil and continue baking for an additional 25 to 30 minutes, or until the potatoes are tender and the top is golden and bubbling.
11 - Allow the dish to rest for 10 minutes before garnishing with chopped chives or parsley and serving.
