01 -
Heat up the oven to 375°F (190°C), then grease your baking dish with butter.
02 -
Peel off the skin and slice those potatoes into thin pieces. Arrange them evenly in the buttered baking dish.
03 -
In a saucepan over medium heat, melt butter and mix in the flour. Keep stirring until smooth. Slowly pour in the cream and milk, little by little, while whisking to keep it lump-free. Toss in onion powder, garlic powder, some salt, and a pinch of pepper. Let it boil, reduce the heat, and keep stirring as it thickens.
04 -
Push the cheddar and mozzarella into the sauce. Keep stirring until it's all melted and creamy.
05 -
Pour half of the cheese mixture over the layered potatoes. Cover everything with foil, then put it into the oven for 30 minutes.
06 -
Take the foil off, pour the rest of the cheese sauce over the dish, and bake uncovered for another hour. Wait until the top is golden and the potatoes are soft.
07 -
Sprinkle parsley or dill on top just before serving. Best enjoyed warm or hot.