3/4 C cake flour, or all-purpose flour
3/4 tsp baking powder
1 pinch salt
1/2 C sugar
1 tsp vanilla extract
2 C raspberries
2 C blueberries
1/3 C powdered sugar, plus extra for dusting
1 C mascarpone
1/2 C heavy cream, chilled
Preheat oven to 350 F degrees. Grease a 9x13 baking dish, line it with parchment paper, and grease parchment paper with butter. Sift flour, baking powder, and salt into a medium bowl.
In a separate bowl, beat eggs until lightened in color, and very thick, about 5 minutes. Add vanilla and sugar. Beat until combined.
Fold flour mixture into eggs. Mix, on low speed, until just incorporated. Pour batter into pan.
Bake for 20 minutes, or until golden brown. Run a knife around the edges to loosen it from the pan. Cool 5 minutes.
Generously dust work surface with powdered sugar. Carefully invert cake pan onto powdered sugar. Gently roll the warm cake up and set aside to cool.
Sift powdered sugar into mascarpone. Whisk to combine.
In a large bowl or mixer, whip heavy cream until stiff peaks form. Fold cream into mascarpone mixture. Fold berries into cream.
Carefully unroll cake. Spread mascarpone and berry mixture evenly over the top.
Re-roll cake, ending with seam side down.
Refrigerate until ready to serve.
Dust with powdered sugar before serving.