Prepare macaroni as directed on the box. Strain and let cool. Grease a 2 quart casserole dish, line bottom with macaroni, 2-3 noodles high. Add salt and pepper to taste and sprinkle on a layer of cheese. Continue layering until pan is full. In a mixing bowl combine milk, dry mustard and eggs. Beat well. Pour mixture over top layer until about 1/2 inch from the top. Bake at 375 degrees for 45 to 55 minutes until bubbling and golden brown. If the top browns too quickly, turn oven down to 350 degrees.