When the cake has cooled down, sprinkle about 2 tablespoons of cocoa powder all over the top of the cake.
Cover the cake with a piece of parchment paper and then top with a baking pan of the same size. Turn the pan with the cake over, remove the baking pan, and carefully peel off the parchment paper.
Reposition the parchment paper over the cake and top it with another baking pan. Invert once more so that the cake is facing right side up again and resting on an inverted baking pan.
Brush 4 tablespoons of the soaking cherry liquid on the surface of the cake.
Spoon half of the whipped cream filling on top, and using an offset spatula, spread evenly.
Arrange the cherries in a single layer over the cream filling, reserving 5 to 6 pieces for the garnish later.
With the short edge close to you, lift the parchment paper and start to roll the cake forward. As you roll, let the parchment paper naturally lift the cake until you reach the other end.
Close the seams of the roll with the cake still wrapped in the parchment paper. Press the cake with your hands as needed, to reinforce the shape.
Transfer the cake to a serving rectangular dish and gently unwrap.
Spoon the whipped cream on the cake and using an offset spatula, smooth out the cream and spread fully cover the roll.
Spoon the remaining whipped cream into a piping bag and pipe swirls or flowers along the length of the cake.
Top each swirl with a piece of cherry. Garnish the cake all over with chocolate shavings.