1 cup unbleached all-purpose flour
1/2 teaspoon baking powder
4 eggs
1/2 cup superfine sugar
1 tablespoon water
Confectioner's sugar for garnish
2/3 cup blackberry jam
Fresh blackberries and pesticide-free rose petals for garnish
Preheat oven to 425. Line bottom of 15x10x1-inch jelly-roll pan with parchment paper. Butter parchment.
Sift flour and baking powder into small bowl. Set aside.
In large mixer bowl, beat eggs and superfine sugar at high speed of electric mixer until thick and creamy, about 5 minutes. Gradually sprinkle flour mixture over egg mixture, then fold in gently. Be sure there are no dry pockets of flour. Fold in water.
Pour batter into pan. Gently spread evenly, smoothing top.
Bake at 425 for 10 minutes until center springs back when lightly touched. While cake is baking, sprinkle a 20-inch-long sheet of parchment paper with sifted confectioners' sugar.
Remove cake from oven and immediately run knife around edge of cake to loosen, then invert hot cake on sugared paper. Peel off baking parchment from bottom of cake. Trim off crusty edges with sharp knife.
Cut both cake and parchment in half crosswise. Gently roll up each hot cake in parchment starting from narrow end. Wrap in clean, warm, damp cloth. Cool on rack.
Before serving, gently unroll cakes. Spread each cake with half the jam, leaving a 1-inch border on all sides. Roll up starting at narrow end.
Cover and refrigerate at least 1 hour.
Cut each cake in 8 to 10 slices. Garnish with berries and rose petals.
