Butter two 9-inch cake pans, Preheat oven to 350°F.
Sift 2 2/3 cups flour, baking soda and salt into medium bowl. Combine cocoa and espresso powder in another medium bowl. Whisk boiling water, then milk and vanilla into cocoa mixture. Using electric mixer, beat sugar, butter and shortening in large bowl until fluffy. Beat in eggs 1 at a time. Add dry ingredients alternately with buttermilk mixture in 3 additions each. Beat batter until smooth, divide between pans.
Bake cakes for 35 minutes, or until toothpick is clean, let cakes cool.
Combine raspberries and sugar in a saucepan and cook over medium heat. Stir mixture until it is a liquid. Stir in gelatin, continue to cook until dissolved. Remove from heat and transfer to a bowl. Refrigerate overnight.
Beat heavy cream on high until stiff peaks form. Add the three tablespoons of sugar and beat until combined.
Mix about a third of the whipped cream into raspberry mixture until well combined. Fold in remaining whipped cream.
Now put a thick layer of jam on the tops of your cakes. take one cake and put some raspberry mousse on the top, cover with 2nd cake. use the rest of your frosting to cover sides and top of the cake.
Feel free to garnish with a few raspberries and some mint.