# List of Ingredients:
→ 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 tbsp unsalted butter
→ Pantry & Spices
08 - 3 tbsp all-purpose flour
09 - 1 tsp garlic powder
10 - 1 tsp salt, plus more to taste
11 - ½ tsp ground black pepper
12 - ¼ tsp smoked paprika
13 - Chopped fresh chives or parsley for garnish (optional)
# Step-by-Step Directions:
01 - Preheat the oven to 375°F. Grease a 9x13-inch baking dish using butter.
02 - Melt the butter in a medium saucepan over medium heat, then whisk in flour continuously for 1 to 2 minutes until bubbly but not browned.
03 - Gradually whisk in whole milk and heavy cream, continuing to whisk until the sauce thickens, about 3 to 5 minutes.
04 - Stir in garlic powder, salt, black pepper, and smoked paprika. Remove from heat.
05 - Add 1½ cups sharp cheddar and ½ cup Gruyère cheese to the sauce, stirring until fully melted and smooth.
06 - Place half the sliced potatoes evenly in the prepared baking dish, then layer half the onions over the potatoes.
07 - Pour half of the cheese sauce evenly over the layered potatoes and onions.
08 - Add the remaining potatoes and onions in an even layer, then pour the remaining cheese sauce on top.
09 - Sprinkle the remaining sharp cheddar and Gruyère evenly over the surface.
10 - Cover the dish tightly with foil and bake for 45 minutes.
11 - Remove the foil and continue baking for an additional 25 to 30 minutes until potatoes are tender and the top is golden and bubbling.
12 - Allow the dish to rest for 10 minutes before garnishing with chopped chives or parsley and serving.
