Preheat & Prep. To start, lightly grease your waffle iron and start preheating it. (I recommend the medium setting if yours is heat adjustable.) Separate Eggs. Carefully separate the egg yolks and egg whites, taking care the NO egg yolk gets into the egg whites. (If it does, the egg whites won't whip!) You will place the egg yolks in a medium bowl, and the egg whites in a large mixing bowl.
Combine Dry Ingredients. In a small bowl, combine gluten-free flour, cornstarch, baking powder, sand salt. Whisk until evenly blended.
Combine Wet Ingredients. In the medium bowl, combine milk, oil, egg yolks, sugar, and vanilla. Whisk to combine.
Whip Egg Whites. In the large bowl, whip the egg whites with a hand mixer on medium-high speed 3-5 minutes, or until you reach stiff peaks. The egg whites will go from translucent and gloopy, to frothy, to white foam. Once you can see the path of the beaters and the egg whites hold their shape when you lift the beaters out of the bowl, you'll know you've got stiff peaks!
Add Dry Ingredients To Wet Ingredients. Stir the dry ingredients into the wet ingredients (not the egg whites!), and mix until evenly combined.
Gently Fold In Egg Whites. Use a spatula to carefully fold 1/3 of the whipped egg white mixture into the waffle batter at a time. Use a folding motion, not a stirring motion so you don't deflate the egg whites. It's ok if the batter looks a bit lumpy at first. You don't need to get the waffle batter perfectly smooth--a few small lumps are ok!
Add Chocolate Chips. Sprinkle in the chocolate chips and gently fold them in.
Cook Waffles. Next, pour batter into the hot waffle iron and cook the waffles according to your manufacturer's instructions until golden brown. (The exact amount of batter per waffle will vary based on the size of your waffle iron!)
Serve & Store. Enjoy warm with your favorite toppings. Store leftover waffles in an airtight container in the fridge 2-3 days or freeze up to 2 months. If freezing, freeze waffles in a single layer or separate layers with parchment paper so they don't stick together!