Heat the oven to 375 degrees.
Place one layer of the potatoes in the bottom of a well greased casserole dish.
Sprinkle salt and pepper over the potatoes.
Melt the butter in a saucepan over medium heat.
Stir in the flour, and mix until well combined.
Whisk in the milk, and simmer until the sauce thickens.
Toss in the cheese and stir until it has completely melted.
Pour half of the cheese mixture over the layer of potatoes.
Top with another layer of potatoes and the remaining cheese mixture.
Bake for 20-25 minutes, or until the potatoes are tender and cooked through.