Combine flour, old bay seasoning, cornmeal, baking powder and soda, sliced onions, cheese, and ¾ cup of the diced black forest ham.
In another bowl, whisk milk with egg and melted butter. Blend milk and egg mixture into the dry ingredients, mixing until all dry ingredients are moistened. Fill 8 muffin cups about 3/4 full. Top each muffin with ½ tsp. of the remaining ham Bake for 25 to 30 minutes.