# Components:
→ 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 (optional garnish)
# Directions:
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 milk and heavy cream. Continue whisking until the mixture thickens, approximately 3 to 5 minutes.
04 - Stir in garlic powder, salt, black pepper, and smoked paprika. Remove the sauce from heat.
05 - Add 1½ cups cheddar and ½ cup Gruyère to the sauce, stirring until fully melted and smooth.
06 - Place half of the sliced potatoes evenly in the baking dish. Spread half of the onions over the potatoes.
07 - Pour half of the cheese sauce over the potatoes and onions. Repeat layering with remaining potatoes and onions, then cover with the rest of the cheese sauce.
08 - Sprinkle the remaining cheddar and Gruyère cheeses evenly over the casserole surface.
09 - Cover the dish tightly with aluminum foil and bake for 45 minutes.
10 - Remove the foil and bake an additional 25 to 30 minutes, until potatoes are tender and the top is golden and bubbling.
11 - Allow the casserole to rest for 10 minutes before garnishing with chopped chives or parsley and serving.
