1. Heat oven to 350 degrees. Lightly grease muffin tins. Mix flour, cornmeal, baking powder, sugar and salt in large bowl. Add cheese and onion; mix well. Add milk, melted butter and eggs; stir just until dry ingredients are moistened. Do not overmix.
2. Spoon into prepared muffin tins, filling two-thirds full. Bake until puffed and golden, 30 to 40 minutes. Cool on wire rack.
