Heat the oven to 200 degrees.
On a medium heat, heat the pan and melt the butter on it. Add the flour to the melted butter and mix until brown. Salt, pepper. Pour in milk and mix.
Remove the pan from the heat and pour the whole mixture into a large bowl. In a separate bowl, roll the potatoes sliced in circles in salt and pepper. Put these circles in our pan on a whip and pour potato milk mixture on top.
Between layers, sprinkle the potatoes with grated cheese; the whole should go with about half the cheese. Sprinkle the other half on top, salt and pepper.
Cover the pan with foil and bake for 60 minutes. Remove the foil and hold for another 10 minutes until golden brown. Remove from oven and let stand for 10 minutes before serving.