Preheat your oven to 350°F (175°C) and prepare two 9-inch round cake pans by greasing them and dusting with gluten-free flour.

In a large mixing bowl, combine the gluten-free flour, granulated sugar, brown sugar, baking soda, salt, and cocoa powder. Whisk thoroughly.

In a separate bowl, mix the buttermilk, vegetable oil, eggs, and vanilla extract until well combined.

Combine the wet and dry ingredients, stirring gently. Slowly add boiling water and mix until smooth.

Divide the batter between the prepared pans and bake for 30-35 minutes. Check for doneness with a toothpick.

While the cakes cool, prepare the frosting by combining sugar, evaporated milk, butter, and egg yolks in a saucepan. Cook for about 10 minutes until thickened, then stir in coconut, pecans, and vanilla extract.

Once the cakes are cooled, assemble by placing one layer on a plate, spreading frosting on top, and adding the second layer. Frost the top and sides.