1-Make the raspberry filling: by whisking together 100 g sugar and 15 g cornstarch in a saucepan, then stir in 120 ml water and 15 ml fresh lemon juice. Heat the mixture over medium until the sugar dissolves, add 150 g fresh raspberries, and cook until it thickens. Let it cool in the refrigerator for later use.

2-Prepare the cake: by preheating your oven to 180°C (350°F) and lining a jelly roll pan with parchment paper. In one bowl, mix 125 g all-purpose flour, 30 g Dutch-processed cocoa powder, 1 tsp baking powder, 1 tsp espresso powder, and 1/4 tsp salt. In another bowl, beat the 4 large eggs’ yolks with 175 g granulated sugar, then add 120 g sour cream, 60 g melted butter, and 1 tsp vanilla extract. Fold the dry ingredients into the wet mixture, then whip the egg whites until stiff peaks form and gently fold them in. Spread the batter in the pan and bake for 10-12 minutes.

3-Right after baking, roll the hot cake in the parchment paper to shape it, then unroll and re-roll it a few times as it cools. This step helps keep the cake flexible and prevents cracks, so handle it carefully.

4-Make the chocolate whipped cream filling by whipping 240 ml cold heavy whipping cream with 40 g powdered sugar, 15 g natural unsweetened cocoa powder, and 1 tsp vanilla extract until stiff peaks form.

5-Carefully unroll the cooled cake and spread the raspberry filling evenly, leaving space near the edges. Pipe the chocolate whipped cream filling over the raspberry layer, then roll the cake again without the parchment and remove any excess filling if needed.

6-Wrap the rolled cake tightly in plastic wrap with the seam side down and refrigerate for at least one hour or overnight to set.

7-Prepare the ganache by heating 120 ml heavy whipping cream until it boils, pour it over 170 g finely chopped semi-sweet chocolate, let it sit for a few minutes, then stir until smooth. Chill the ganache until firm, then reheat it slightly until it’s spreadable.

8-Spread the ganache evenly over the chilled cake roll and decorate with additional chocolate whipped cream and raspberries if you like. Serve it right away or wait for the ganache to firm up.