# What You’ll Need:
→ 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 additional to taste
11 - ½ teaspoon ground black pepper
12 - ¼ teaspoon smoked paprika
13 - Chopped fresh chives or parsley, for garnish (optional)
# Step-by-Step Guide:
01 - Preheat oven to 375°F. Generously butter a 9x13-inch baking dish to prevent sticking.
02 - Melt butter in medium saucepan over medium heat. Add flour and whisk continuously for 1 to 2 minutes until mixture is bubbly but not browned.
03 - Gradually add whole milk and heavy cream while whisking. Continue whisking until sauce thickens, about 3 to 5 minutes.
04 - Incorporate garlic powder, salt, pepper, and smoked paprika into sauce. Remove from heat.
05 - Stir in 1½ cups cheddar and ½ cup Gruyère until completely melted and smooth.
06 - Arrange half of the sliced potatoes evenly in baking dish. Top with half the onions in an even layer.
07 - Pour half of the cheese sauce evenly over the potatoes and onions.
08 - Layer remaining potatoes and onions, then cover with the rest of the cheese sauce.
09 - Evenly sprinkle remaining cheddar and Gruyère over the top.
10 - Cover dish tightly with aluminum foil and bake for 45 minutes.
11 - Remove foil and continue baking for 25 to 30 minutes until potatoes are tender and top is golden and bubbling.
12 - Allow dish to rest for 10 minutes before garnishing with chives or parsley and serving.
