Boil macaroni in salted water, drained, rinsed with cold water and poured over a heated half butter. In a baking dish, greased with butter, pour half of the cooked pasta and sprinkle with shredded feta cheese. Cover with the second half of the pasta and pour the Bechamel prepared from the remaining butter, which fry flour and mixed with cold milk. Season to taste with salt. Pasta bake in very hot oven until it turns rosy. Serve warm, with scatter the grated cheese. Separately served tomato sauce.