# List of ingredients:
→ 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 additional to taste
11 - ½ teaspoon ground black pepper
12 - ¼ teaspoon smoked paprika
13 - Chopped fresh chives or parsley, for garnish (optional)
# How to make it:
01 - Preheat oven to 375°F and 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 for 3 to 5 minutes until the mixture thickens.
04 - Stir in garlic powder, salt, black pepper, and smoked paprika. Remove from heat.
05 - Mix in 1½ cups shredded cheddar and ½ cup shredded Gruyère until smooth and melted.
06 - Arrange half of the sliced potatoes evenly in the prepared dish and top with half of the sliced onions.
07 - Pour half of the cheese sauce over the potato and onion layers.
08 - Place the remaining potatoes and onions over the sauce, then cover with the rest of the cheese sauce.
09 - Sprinkle the remaining cheddar and Gruyère cheeses evenly over the top.
10 - Cover tightly with aluminum foil and bake for 45 minutes.
11 - Remove foil and bake an additional 25 to 30 minutes until potatoes are tender and the top is golden and bubbling.
12 - Allow casserole to rest for 10 minutes before garnishing with chives or parsley and serving.
