Preheat the oven to 350F and line a standard cupcake tin (or muffin tin) with cupcake liners. Set aside

In a small bowl combine the gluten-free flour, cornstarch, baking powder, and kosher salt and set aside.

In a medium bowl combine the granulated white sugar, eggs, vanilla extract, and oil. Whisk until the mixture is light and the sugar is fully dissolved.

Add half of the dry ingredients and half of the milk to the oil mixture and whisk together. Repeat with the remaining ingredients and whisk until smooth.

Using a large cookie scoop equally divide the gluten-free vanilla cupcake batter. Make sure to only fill each cavity ¾ full.

Bake the cupcakes at 350F for 20-22 minutes until golden and a toothpick inserted in the center of a cupcake comes out clean.

Remove the gluten-free cupcakes from the oven and allow for them to cool in the pan for 5 minutes before transferring them to the cooling rack to cool completely before frosting.

Cream the butter, vanilla extract/paste, and salt for 2-3 minutes in the bowl of a stand mixer or a large mixing bowl.

With the mixer running on low, add the powdered sugar and cocoa powder one third at a time. Make sure to scrape down the sides in between additions.

Once all the dry ingredients have been added, turn up the speed of your mixer and mix for 2 minutes.

Add milk/heavy cream as needed to thin out the frosting.