Preheat the oven to 370. Coat 12 2½" muffin cups with nonstick cooking spray or insert cupcake liners. In a large bowl, stir together the flour, cornmeal, baking powder, mustard, baking soda and salt. Stir in the chopped chicken and make a well in the center.
In a 1-pint measuring cup, stir together the buttermilk, oil, egg whites and honey. Pour the liquid into the dry ingredients and stir just until combined.
Fill each muffin cup about ¾ full. Bake for 20-25 minutes. Will keep, wrapped in aluminum foil and refrigerated, for 2 days. Makes 12 muffins.