To prepare a cinnamon vanilla wedding cake with mexican hot chocolate buttercream 1973 recipe, first you'll need to prepare the cake batter. First, combine the flour, baking powder, cocoa, sugar, and salt. Then, add the wet ingredients to the dry ingredients and mix until combined. Next, pour the batter into the greased and floured cake pan and bake for 35 to 40 minutes, or until toothpick inserted in the center comes out clean.