To give this cake the beverage's trademark kick, Wendy Kromer spread dark-chocolate buttercream spiked with chili powder between slabsof cinnamon-vanilla cake.
Trim the tops of the cake layers so that they are level and measure approximately 3/4- to 7/8-inches high.
Place one cake layer onto a corresponding-size cardboard round, brush with simple syrup, and then spread with approximately 3/4 to 1 cup of the buttercream. Set another cake layer on top, and continue assembly until the last cake layer has been added. Once assembled, frost entire tier with remaining buttercream.