Mix the first 4 ingredients till smooth. Pour vinegar over the baking soda. The reaction will produce foam. Mix the foam into the batter.
Pour the mixture in the dish, and bake for 35-40 min or until a toothpick comes out of the center clean and dry.
Remove from the dish and let cool on a wire rack.
To prepare the cream, blend sour cream and sugar with a hand mixer till the mixture starts thickening. Add the liquor and let blend in.
Grind chocolate on a mid-small grinder.
After the cake is cool, carefully cut the sides off and cut the cake into ~ 1/2 inch layers.
Spoon a little bit of sour cream mixture on the bottom of a cake stand. Place the first layer on it. Generously layer sour cream mixture on top of the cake. Place another cake layer on top, repeat with the remaining layers. Sprinkle the top layer with the chocolate flakes. Cover the cake and let stand in the fridge overnight for the flavors to blend .