Place the egg yolks, vanilla extract, oil and buttermilk in another large bowl and mix to combine. Pour this wet mixture over the dry ingredients and whisk well, making sure there are no lumps.
Whisk the egg whites to firm peaks in a clean bowl.
Gently and slowly fold the egg whites into the batter, a little at a time until you have a light, smooth, airy batter.
Preheat your waffle maker according to the manufacturer's instructions. Pour the batter into the waffle maker. My waffles took about 8 minutes to cook all the way through, but yours may need more or less depending on your waffle maker. Mine is a deep fill waffle maker so they do take a little longer.
When the waffles are ready, you can either transfer to a plate or place them in a low oven to keep warm.
Serve the waffles with the vanilla apples, Greek yoghurt or whipped cream.