Triple Chocolate Mousse Cake – Garden & Gun

For the cake: Preheat the oven to 350°F. Grease two (8-inch) round cake pans (I use vegetable shortening) and dust with cocoa powder. Stir together the flour, cocoa powder, baking soda, baking powder, and salt in a medium bowl. Beat the mayonnaise and sugar with an electric mixer until creamy. Add the eggs, one at a time, until combined. Add the flour mixture alternately with the water, beginning and ending with the flour mixture. Beat at medium-low speed for 1 minute. (Batter will be thin.) Stir in the vanilla. Pour the batter evenly into the prepared pans. Bake the cakes at 350°F for 21 to 24 minutes, until a toothpick inserted in the center comes out clean. Remove to wire racks. Let cool in the pans for 5 minutes. Run a knife around the edges and turn out onto wire racks to cool completely. Once cooled, split each layer in half. Make the ganache frosting and the chocolate mousse filling. Place one cake layer on a cake plate or stand. Top with one-third of the chocolate mousse filling; repeat the process twice. Place the remaining cake layer on top. Spread the ganache frosting on the top and sides of the cake before slicing. For the ganache frosting: Place the chocolate in a medium bowl. Heat the cream and corn syrup in a small saucepan until the cream is hot. Pour over the chocolate. Let stand for 1 minute, then stir until smooth. For a shiny look, let stand until spreadable (20 to 30 minutes), stirring occasionally. For fluffy chocolate frosting, beat the mixture with an electric mixer until fluffy. For the chocolate mousse filling: Sprinkle the gelatin over the cold water in a small bowl. Let stand until the gelatin softens. Stir in the boiling water to dissolve the gelatin. Place the chocolate in a medium bowl. Heat ½ cup of the cream and the sugar in a small saucepan over medium heat until the sugar dissolves and the cream is steaming. Pour over the chopped chocolate; add the gelatin and stir until smooth. Beat the remaining 1 cup cream with an electric mixer until stiff peaks form. Fold a small amount of whipped cream into the chocolate; gently fold in the remaining whipped cream until combined. Use immediately. (The mixture will firm up as it stands.)