I made my own birthday cake this year. I doubled this brownie recipe, and added some shredded coconut to spice it up a little. I baked it in two square pans. I then doubled this recipe for healthy chocolate avocado icing. Both of these recipes are sugar free and gluten free.
I made a cake platform out of cardboard and aluminum foil, and once the brownies finished baking I put the first one down as the first layer. I then spread some of the icing on it, and lay the second brownie on top as the top layer. I used the rest of the icing to cover up the sides and top of the cake. The result was this nice simple chocolate cake.