# What You Need:
→ Potatoes
01 - 3 pounds Yukon Gold or Russet potatoes, peeled and thinly sliced (about 1/8 inch)
→ Cheese Sauce
02 - 4 tablespoons unsalted butter
03 - 1 medium yellow onion, finely chopped
04 - 3 cloves garlic, minced
05 - 4 tablespoons all-purpose flour
06 - 2 1/2 cups whole milk, warmed
07 - 1 cup heavy cream
08 - 2 teaspoons Dijon mustard
09 - 1 teaspoon salt
10 - 1/2 teaspoon black pepper
11 - 1/2 teaspoon smoked paprika
12 - 2 cups sharp cheddar cheese, shredded
13 - 1 cup Gruyère cheese, shredded
→ Topping
14 - 1/2 cup shredded cheddar cheese
15 - 1/2 cup shredded Gruyère cheese
16 - 2 tablespoons chopped fresh chives (optional)
# Directions:
01 - Preheat oven to 350°F. Grease a 9x13-inch baking dish with butter or nonstick spray.
02 - Place half of the sliced potatoes in an even layer in the prepared baking dish.
03 - In a large saucepan over medium heat, melt butter and sauté the chopped onion for 4 to 5 minutes until softened. Add garlic and cook for an additional minute.
04 - Sprinkle in flour and stir constantly for 1 to 2 minutes to form a roux.
05 - Gradually whisk in warmed milk and cream, stirring continuously until smooth and thickened, about 3 to 4 minutes. Stir in Dijon mustard, salt, black pepper, and smoked paprika.
06 - Remove from heat and whisk in shredded cheddar and Gruyère cheeses until fully melted and smooth.
07 - Pour half the cheese sauce over the first potato layer. Top with remaining potatoes and pour over the remaining cheese sauce evenly.
08 - Cover the dish with foil and bake for 45 minutes.
09 - Remove foil, sprinkle remaining shredded cheddar and Gruyère cheese over the top, and bake uncovered for 25 to 30 minutes until potatoes are tender and topping is golden and bubbly.
10 - Let stand for 15 minutes before serving. Garnish with chopped fresh chives if desired.
