In a large mixing bowl, combine the all-purpose flour, unsweetened cocoa powder, granulated sugar, baking powder, and salt. Whisk everything together until well combined.
Add the cold and cubed unsalted butter to the dry mixture. Use a pastry blender or fingers to cut the butter into the dry ingredients until the mixture resembles coarse crumbs. This is what will give your biscuits a flaky texture.
Whisk in teh eggs, then pour the whole milk and pure vanilla extract. Stir until the ingredients are just combined. If you're using chocolate chips, fold them in at this point.
Lightly flour a work surface and turn out the dough. Press the dough out to about a 1-inch thickness. Use a round biscuit cutter to cut out biscuits. Reform the scraps and continue cutting biscuits until you've used all the dough.
Preheat your air fryer to 330°F (165°C). If your air fryer doesn't have a preheat setting, just run it at the cooking temperature for about 5 minutes.
Place them in a single layer in the air fryer basket, ensuring they aren't touching. Depending on the size of your air fryer, you may need to do this in batches. Cook at 330°F (165°C) for 8-10 minutes or until the biscuits have risen and are cooked. You can test for doneness by inserting a toothpick in the center of a biscuit. The biscuits are done if it comes out clean or with a few crumbs.
Remove the biscuits from the air fryer and let them cool on a wire rack for a few minutes before serving. Enjoy your homemade air fryer chocolate biscuits warm!