Instructions
Preheat oven to 350˚F. Line the bottom of an 18×13 baking sheet with parchment paper (do not grease).
Add 5 eggs to the bowl of a stand mixer fitted with whisk attachment and beat on high speed 1 min, or until foamy. Gradually add sugar and beat on high 7 min. It will be thick, fluffy and tripled in volume**
Whisk together flour and baking powder and sift into egg batter one third at a time, folding to incorporate between each addition and scraping from the bottom to catch hidden flour pockets. Stop mixing when you no longer see streaks of flour.
Transfer to lined baking sheet and bake right away at 350˚F for 13-15 min (mine took 15 min) or until top is golden. Remove from oven and right away run a thin edged spatula or knife around edges of your cake to loosen from the pan. While cake is hot***, invert cake face down onto a clean, dry linen towel, remove parchment paper then roll cake into the towel. Let cool to room temp (30 min – 1hr) in a draft free room.
Meanwhile, combine all ingredients for lemon syrup (water, sugar, lemon juice), stir to dissolve sugar and set aside.
In a large mixing bowl, combine 8 oz softened cream cheese, 8 Tbsp softened butter and 1 cup powdered sugar. Beat together starting on low speed to incorporate sugar, then turn the mixer up to high speed for 2-3 min or until whipped, white and fluffy, scraping down the bowl as needed. Add coarsely chopped blackberries and stir into cream with mixer on low, just until incorporated.
Carefully Unroll cake and loosen from the towel. Brush the top evenly with your lemon syrup. Put dollops of blackberry frosting over the surface and spread evenly. Roll the cake tightly in the same direction you rolled it the first time. Slice off the edges if desired and dust generously with powdered sugar.
For the topping, beat together 3/4 cup heavy cream with 1 Tbsp powdered sugar for 2 min on high speed until fluffy and spreadable. Transfer to a large piping bag with a large open star tip and pipe 6 flowers over the top, placing a fresh blackberry and lemon triangle into the center of each one.
Notes
**Sponge cakes rely on the volume of the whipped eggs to rise properly. It is extremely important to beat the eggs and sugar for the time stated.
***To prevent cracks in cake roll, it should be rolled in the linen towel right after it comes out of the oven.
