Heat oven to 400 degrees F. Spray a 9-inch square baking pan with non-stick cooking spray.
Combine flour, cornmeal, sugar, baking powder, and salt in a large bowl. Set aside.
In a separate smaller bowl, whisk together milk, oil and egg or egg whites. Pour the wet ingredients over the dry and, using a fork, stir until just combined. Do not overmix. Spread batter evenly in pan and bake 20 to 25 minutes, or until a toothpick inserted in the center comes out clean. Cut into squares or triangles and serve immediately.