Whip the CREMIO pastry crèmе. Finely grind the walnuts in a food processor. In a large bowl, mix the sour cream and powdered sugar by hand, then add the whipped CREMIO pastry crèmе.
On a cake plate, start layering the honey cake sheets, spreading the cream mixture between each layer and adding a drizzle of blueberry jam. Cover the sides of the cake with the remaining cream, and finish the top with a generous layer of blueberry jam.
Sprinkle the entire cake with the ground walnuts and refrigerate for 12 hours. Serve decorated with fresh blueberries.