1/2 lb. med. shells
1 tsp. butter
1 beaten egg
1 tsp. salt
1 tsp. dry mustard
3 c. grated sharp cheese
1 c. milk

Boil shells in water until tender and drain thoroughly. Stir in butter and egg. Mix mustard and salt with 1 tablespoon hot water and add to milk. Add cheese, leaving enough to sprinkle on top. Pour shells into a buttered casserole. Add milk mixture, sprinkle with remaining cheese. Bake at 350 degrees for about 45 minutes or until custard is set and top is golden brown.