In a large bowl, combine the corn bread mix, egg and milk. Spread into a greased 13x9-in. baking pan. Bake at 400° for 9-11 minutes or until a toothpick inserted in the center comes out clean. Cool on a wire rack.
Cut corn bread into 1-1/2-in. squares. Top each with spinach, crawfish, mayonnaise and a jalapeno slice.