Peel and thinly slice 2-3 pounds of potatoes (Yukon Gold or Russet work well).
In a saucepan, melt 4 tablespoons of butter over medium heat
Whisk in 1/4 cup of all-purpose flour to create a roux.
Gradually pour in 2 cups of milk, whisking constantly until smooth and thickened.
Season the sauce with salt, pepper, and a pinch of nutmeg.
Layer half of the sliced potatoes in a greased baking dish, then pour half of the sauce over them.
Repeat with the remaining potatoes and sauce. Cover with foil and bake for 45 minutes, then remove the foil and bake for an additional 15-20 minutes until golden brown and bubbly. Enjoy!