When the yellow cake is completely cool and slightly chilled, use a serrated knife to level the cake by removing the dome from the top of the cake.
Once the cake has been leveled, divide the cake horizontally into two, equal layers. Use your hands and a pastry brush to brush away any excess crumbs.
Once you've brushed away any excess crumbs from the cake layers, brush the top of each cake layer with a generous amount of simple syrup. Each cake should receive about a 1/8 cup of simple syrup.
Set your bottom cake layer on a work surface (or a serving platter) and scoop about 1 cup chocolate ganache frosting on top, using an offset spatula to spread it evenly across the cake top. Nestle the second cake layer on top, and use the remaining chocolate ganache frosting to cover the cake entirely. I decorated my cake with messy swirls and chocolate chips, but you can opt for the smooth or piped look if you prefer — the recipe gives you plenty of frosting to play with. Enjoy!