Triple Chocolate Roll Cake

Prepare the White Chocolate Whipped Cream: Place white chocolate chips and 3/4 cup heavy cream in a medium microwave-safe bowl. Microwave at 50% power in 30-second intervals, stirring in between, until melted and smooth (approx. 2 minutes). Cool to room temperature (10-20 minutes), then refrigerate until completely chilled (at least 4 hours to overnight).

Prepare the Dark Chocolate Mousse: Place dark chocolate chips and 3/4 cup heavy cream in a separate medium microwave-safe bowl. Microwave at 50% power in 30-second intervals, stirring in between, until melted and smooth (approx. 2 minutes). Cool to room temperature (10-20 minutes), then refrigerate until completely chilled (at least 4 hours to overnight).

Preheat and Prepare: Preheat oven to 350°F (175°C). Line a 12x17-inch baking sheet with parchment paper; grease both the baking sheet and parchment paper.

Make the Cake Batter: In a large bowl, beat egg yolks and brown sugar with an electric mixer on medium-high speed until light and creamy (approx. 2 minutes). Beat in melted butter, cooled coffee, and vanilla extract.

Combine Dry and Wet Ingredients: In a separate bowl, sift together flour, 1/3 cup cocoa powder, baking powder, baking soda, and salt. Gradually add to the egg yolk mixture, mixing until just combined.

Whip Egg Whites: In a clean, dry bowl, beat egg whites with an electric mixer on high speed until soft peaks form. Gradually add sugar, 1 tablespoon at a time, continuing to beat until glossy and stiff peaks form.

Fold in Egg Whites: Gently fold 1/3 of the egg white mixture into the yolk mixture to lighten it. Then, gently fold in the remaining egg white mixture until just combined. Be careful not to overmix.

Bake the Cake: Pour the batter into the prepared baking sheet, spreading it evenly. Bake in the preheated oven until the cake springs back lightly when touched (approx. 10 minutes). Avoid overbaking.

Prepare for Rolling: While the cake is baking, lightly sprinkle a piece of parchment paper (slightly larger than the baking sheet) with the remaining 1 tablespoon of cocoa powder.

Invert and Cool: Run a table knife around the edges of the baking sheet to loosen the cake. Invert the cake onto the prepared cocoa-dusted parchment paper. Remove the parchment paper the cake was baked on. Working quickly, roll the cake and cocoa-sprinkled parchment paper together, starting from a narrow end. Place the cake, seam-side down, on a wire rack to cool completely (1-2 hours).

Whip the White Chocolate Cream: Once chilled, whip the white chocolate mixture with an electric mixer, starting on low and gradually increasing to medium-high speed, until light and fluffy (1-2 minutes). Add 3/4 cup heavy cream and beat until it reaches a whipped cream consistency (1-2 minutes). Transfer to a piping bag or a resealable plastic bag with a 1/2-inch hole cut into a corner. Refrigerate until ready to use.

Whip the Dark Chocolate Mousse: Once chilled, whip the dark chocolate mixture with an electric mixer, starting on low and gradually increasing to medium speed, until it crumbles and lightens in color and texture (1-2 minutes). Add the remaining 3/4 cup heavy cream and beat on medium-high speed until smooth, light, and fluffy (1-2 minutes). If needed, add more heavy cream to achieve the desired lightness and consistency of whipped mousse. Transfer to a piping bag or a resealable plastic bag with a 1/2-inch hole cut into a corner. Refrigerate until ready to use.

Assemble the Cake: Gently unroll the cooled cake and discard the parchment paper. Pipe the white and dark chocolate fillings in alternating vertical stripes (about 1/2-inch thick) along the 12-inch side of the cake, leaving about a 1/2-inch border on all sides.

Roll and Chill: Gently reroll the cake over the fillings (without parchment) as tightly as possible without breaking the cake. Place on a serving platter and refrigerate until set (at least 1 hour).

Slice and serve