Preheat oven to 350ºF.In a medium-size bowl, combine egg yolks, milk, vanilla, and melted butter and stir.Add the cornmeal, flour, sugar, baking powder, and salt. Stir until fully combined, but do not over mix.In a separate bowl, beat the egg whites until stiff peaks form. Carefully fold them into the batter.Pour batter into a greased 9x13 inch pan and bake for 25-30 minutes or until an inserted toothpick comes out clean.