In a large bowl whisk together the flour, corn flour, baking powder, sugar and salt. Set aside.
In another mixing bowl, whisk together milk, egg yolks, melted butter, oil and vanilla until combined. Pour the wet ingredients into the dry ingredients and whisk until smooth. Set aside.
In the bowl of your mixer or using a hand whisk, whisk the egg whites until stiff peaks form. Using a spatula, gently fold the egg whites into the batter.
Leave to rest for 30 minutes in the fridge. Pre-heat oven to 100°C. Place a wire rack on a baking tray and place in the oven.
Pre-heat waffle iron. For smaller waffles, pour 1 medium cookie scoop of batter , for larger waffles pour 1/3 cup of batter into each well of the waffle maker. Cook the waffles until golden brown and crisp, for 4 minutes. Place the cooked waffle on the wire rack, in the oven. Cook remaining batter.