Heat oven to 400° F (375° F for dark pan). Coat 24 miniature (1 ¾-inch) or 8 standard muffin cups lightly with no-stick cooking spray.
Combine cornbread mix, mustard, milk, sour cream and egg in large bowl. Stir until smooth. Stir in cheese and bacon. Fill muffin cups ¾ full.
Bake 12 to 15 minutes or until light brown. Remove muffins to wire rack; cool slightly before serving.