Preheat your oven to 350°F (175°C).
Prepare your baking pans by greasing and flouring two 9-inch round cake pans.
In a large mixing bowl, combine the gluten-free flour, granulated sugar, cocoa powder, baking powder, baking soda, and salt. Whisk thoroughly.
Add the eggs, whole milk, vegetable oil, and vanilla extract to the dry ingredients. Beat on medium speed for 2 minutes.
Carefully stir in the boiling water until combined.
Pour the batter evenly into the prepared cake pans.
Bake for 30-35 minutes, checking for doneness with a toothpick.
Allow the cakes to cool in the pans for 10 minutes before transferring to wire racks to cool completely.