I had some blackberry schnapps in my cabinet and thought, hmm.... I wonder what would be good with this and this cake was born, I have made it many times since. My Uncle requests it every year for his birthday, or any day he thinks he can talk me into making it :)
Preheat oven to 350 degrees. Prepare cake mix as directed and divide between two 9 inch greased and floured cake pans. Bake until toothpick inserted in center of cakes comes out clean. Cool in pan on wire racks, ten minutes, flip cakes out onto wire racks and cool completely.
While cakes are cooling in a small saucepan add water, schnapps (off flame) and sugar to create a simple syrup that will be brushed onto cooled cake. Heat until sugar is dissolved and take off heat to cool.
In a small bowl, mix jar of blackberry jam and three tbsp of schnapps (to slightly thin the jam) and set aside
Once cakes are completely cooled slice them into two layers for a total of four layers. Place bottom layer on cake board or plate and brush with simple syrup mixture. Add 1/4 of jam mixture and spread evenly on cake layer. Repeat this step for next two layers.
Prepare pudding with 1 1/2 cups of milk and allow to set partially before folding whipped topping into the pudding mixture. This will be your frosting for the cake.
Once top and sides of cake are frosted I recommend piping remaining frosting along the top edges of the cake before "filling" with the remaining jam mixture. If you are not sure you want to pipe the frosting on the top you can attempt to make a well on the edges. The jam mixture is a bit runny so you want to make sure you have something to stop it from running down the sides of the cake when you add it to the top. piping the frosting works best for this.