Preheat the oven to 350ºF. Lightly grease a 9x9 baking pan with cooking spray. (You can also use a 9x13 pan and the cornbread will be thinner.)
In a medium bowl, combine the egg yolks, milk, vanilla, and melted butter. Whisk until well-combined.
In a separate bowl, beat the egg whites until stiff peaks form.
In a large bowl, add the cornmeal, gluten-free flour, sugar, baking powder, and salt. Stir to evenly combine.
Pour the wet ingredients into the dry ingredients and mix until just combined. Using a rubber spatula, carefully fold the egg whites into the batter.
Pour batter into the pan and bake for 25-30 minutes, or until an inserted toothpick comes out clean.
Let cool for 10 minutes. Slice and enjoy!