1. Preheat oven to 350°.
2. Weigh or lightly spoon flour into dry measuring cups; level with a knife. Combine flour and next 5 ingredients (through pepper) in a medium bowl; stir with a whisk. Make a well in center of mixture. Combine buttermilk, egg substitute, and oil; add to flour mixture, stirring just until moist. Fold in cheese, green onions, corn, and diced ham.
3. Spoon batter into 12 muffin cups coated with cooking spray. Bake at 350° for 23 minutes or until a wooden pick inserted in center comes out clean. Remove muffins from pan; place on a wire rack.