Prepare the Chocolate Sponge Cake:

1. Preheat the Oven: Preheat your oven to 350°F (175°C). Line a 10×15-inch jelly roll pan with parchment paper, greasing it lightly for easy removal.

2. Mix the Wet Ingredients: In a large bowl, whisk eggs and granulated sugar until light and fluffy, about 5 minutes. Add vanilla extract and warm water, mixing until combined.

3. Combine Dry Ingredients: In a separate bowl, sift together flour, cocoa powder, baking powder, and salt. Gradually fold into the wet ingredients with a spatula.

4. Bake the Cake: Pour the batter into the prepared pan, spreading evenly. Bake for 10-12 minutes until the cake is firm to the touch and a toothpick inserted comes out clean.

5. Roll the Cake: Immediately turn the cake onto a kitchen towel dusted with powdered sugar. Peel off parchment and roll the cake in the towel. Let cool completely in this shape.

Prepare the Raspberry Filling:

1. Cook the Raspberries: In a medium saucepan, combine raspberries, sugar, and lemon juice over medium heat, stirring until berries break down (5-7 minutes).

2. Thicken the Filling: Add the cornstarch-water mixture and stir until thickened. Remove from heat and let cool completely.

Prepare the Whipped Cream:

1. Whip the Cream: In a chilled bowl, beat the heavy cream, powdered sugar, and vanilla extract until soft peaks form.

Assemble the Swiss Roll:

1. Unroll the Cake: Once cooled, carefully unroll the cake from the towel.

2. Add the Raspberry Filling: Spread the cooled raspberry filling evenly on the cake, leaving a small border along the edges.

3. Add the Whipped Cream: Spread whipped cream on top of the raspberry filling.

4. Roll the Cake: Gently roll the cake back up and transfer it to a serving platter, seam side down.

Decorate and Serve:

1. Garnish: Garnish with fresh raspberries, chocolate shavings, and powdered sugar if desired.

2. Serve: Slice into even portions and serve. Enjoy!