Preheat oven to 350 degrees F, and line two 6-inch round cake pans with parchment paper. Spray with cooking oil. In a large bowl, mix together flour, sugar, cocoa powder, baking powder, baking soda, and sea salt. 1 cup gluten free all-purpose flour, 3/4 cup granulated white sugar, 1/2 cup cocoa powder, 1 tsp baking powder, 1 tsp baking soda, 1/2 tsp sea salt
Add milk, oil, egg, and vanilla extract to the flour mixture. Use a handheld mixer to mix at medium speed until combined.
1/2 cup milk, 1/4 cup avocado oil, 1 egg, 1 tsp vanilla extract
Reduce to low speed and slowly drizzle in boiling water while mixing. Once all the water is added, increase to high speed for 1 minute until fully combined.
1/2 cup boiling water
Divide the batter into prepared caked pans, and bake for 35-40 minutes until a toothpick inserted in the center comes out clean.
Cool for 10-15 minutes, then remove from the pan and transfer to a wire rack to cool completely before frosting.
Using a stand mixer with the paddle attachment or an electric mixer, add all ingredients for the buttercream frosting to a bowl and whisk on low speed until everything is combined. Switch to high speed for 8-10 minutes, scraping down the sides halfway through. The frosting should be smooth a creamy.
1 cup butter, 1½ tbsp milk, 1 tsp vanilla extract, 1/8 tsp sea salt, 3 cups powdered sugar
Add food dye to the frosting if you want. If you cake layers are domed on the top, you can use a use a serrated knife to trim the dome to level out the layers. Spread an even layer of frosting in between the two cake layers. Frost the cake however you wish!