In a rectangular or square tray, arrange a layer of biscotti dipped in coffee. If needed cut some of the biscotti in half to make them fit in the tray perfectly.
Beat the confectionery cream to stiff snow and mix it with 1-2 tsp of jam.
Beat the soft butter with 2 tbsp powdered sugar and add to the confectionery cream and jam. Mix well.
Divide the cream into 3 parts. Smear the 1st layer of biscotti with 1 part of the cream.
Arrange another layer of soaked in coffee biscotti and smear with cream. Distribute blueberry jam again but leave a little aside for garnishing.
Arrange another layer of biscotti, smear with cream. Decorate the cake by spraying whipped cream on top.
Before serving, sprinkle cocoa and chocolate sprinkles over the cake. Serve each slice with whipped cream on top and a tsp of blueberry jam.