I worked with Jemma’s Polka Dot Swiss Roll Recipe to get this.
50 g unsalted butter, softened
50 g powdered sugar, sifted
2 eggs whites
30g flour, sifted
20 g cocoa powder, sifted
3 large eggs, separated
80 g sugar (in 2x 40g batches)
45 g unsalted butter, melted
75 g plain flour, sifted
½ tsp vanilla extract
120ml whipping cream
Preheat oven to 350 degrees F and line a jelly roll pan with parchment paper.
For the stripes, add butter and icing sugar to a small bowl and mix with hand mixer until well blended. Add the egg whites and mix again until blended. Sift in cocoa powder and flour and mix until blended. Fill piping bag and pipe out any design you desire. Place in refrigerator while make Swiss roll batter.
For Swiss Roll batter, separate eggs and using hand mixer mix egg whites and 40g of sugar until stiff peaks. Then mix yolks and sugar until lighter in color and thicker. Mix in vanilla extract. Fold egg whites into yolks in three stages. Then fold in the melted and cooled butter and flour (do this in two batches starting and ending with flour).
Carefully spread Swiss Roll batter over the refrigerator pattern and bake for approximately 10 minutes when the center springs back.
Cut a border around the cake while hot and turn out cake onto a baking tray. Flip cake back onto a tea towel and cover exposed end with parchment paper. As you roll the warm cake, remove the bottom parchment (watch Jemma’s video above for exactly how to do this). Then re-roll the tea towel around the cake until you are ready to fill. This keeps the cake from cracking and moist.
Make whipped cream and then unroll cake. Apply a layer of jam leaving a 1/2 inch border and then cover with whipped cream. Don’t go too thick on either layer. Re roll cake and refrigerate until ready to serve.