In a bowl, combine dry ingredients. In another bowl, beat egg slightly and add milk and corn. Sauté onion and jalapeno in a skillet with butter until onion is translucent. Add milk mixture, onion mixture, and cheese to dry ingredients. Stir until well combined. Pour into a well-buttered 8" square pan. Bake at 400°F for 35-40 minutes or until a toothpick inserted in the center comes out clean.