Preheat the oven to 325. Spray 4 - 8- inch cake pans well with bakers spray
In a bowl whisk together cocoa powder, hot coffee and sour cream until smooth. Cool to room temperature
In another bowl combine the flour, baking powder, baking soda and salt, set aside
In a third bowl beat butter and sugars until light and fluffy
Add eggs one at a time beating in each egg, then beat in vanilla
Add the flour mixture alternating with coffee/cocoa mixture and mix just until blended
Divide batter between pans and bake 20 to 30 minutes until a toothpick comes out just clean. Cool in pans 10 minutes then remove to racks to cool completely
Make Marscapone Filling and Frosting
Beat cream until it holds its shape
In another bowl beat mascarpone, sugar, salt, and vanilla
Fold mascarpone into whipped cream in 3 additions until fully incorporated. If filling seems very soft refrigerate about an hour to firm up for easier filling and frosting.
Assemble Cake
Place one cake layer, bottom facing up on serving plate
Add some Mascarpone Cream filling
Place second cake layer on first, bottom up
Spread with more filling
Add third cake layer and spread with some filling
Add fourth final cake layer an frost entire cake with remaining frosting. Chill at least 1 hour before adding coffee glaze
Make Coffee Glaze
In a bowl whisk together coffee and confectioner's sugar and vanilla until smooth
Pour coffee glaze directly over top of cake allowing it to flow over sides. Garnish with dark and white chocolate shavings. Refrigerate to set glaze before slicing.
