Amish Tuna Casserole

1-8 ounce package noodles
3 1/2 tablespoons butter
3 tablespoons flour
2 - 2 1/2 cups milk
1/2 cup grated cheese
1-7 ounce can tuna

Cook noodles until tender. Drain and put in baking dish. Add tuna and mix slightly. Use remainder of ingredients to make a white sauce. Melt butter, then mix in flour. Add milk and cheese (optional) and seasonings. Stir until sauce thickens. Pour over noodles and tuna. Bake in over at 350 for 30-40 minutes.