Cook Creamettes spaghetti according to package directions. In skillet, brown beef in butter, stirring occasionally. Remove from heat. Add 1/4 cup flour, nonfat dry milk, salt, pepper and half of soup mix. Blend, gradually stir in water. Cook, stirring constantly, till thickened. Combine remaining soup mix with 1 tablespoon flour, then blend with sour cream; fold into cooked spaghetti. Turn spaghetti into 2-quart buttered casserole, pushing up sides to leave a "well" in center. Pour meat mixture in center. Top with buttered crumbs. Bake 25 minutes in 350 degrees F. oven, or til crumbs brown. 6 servings.