Ingredients
1 tablespoon plus 1 1/2 teaspoons butter, room temperature, for baking sheet
1/4 cup all-purpose flour, for dusting
3 medium egg yolks
1 3/4 cups confectioners’ sugar, plus more for dusting
4 medium egg whites
1/2 cup unsweetened cocoa
1 tablespoon plus 1 1/2 teaspoons potato flour
1 generous cup heavy cream
1 generous cup Raspberry Coulis for Roulade Marquis
1 1/4 cups fresh raspberries
Preparation
Preheat oven to 425 degrees. Line a rimmed baking sheet with parchment paper; butter and flour parchment paper and set aside.
In the bowl of an electric mixer fitted with the whisk attachment, beat yolks and scant 1 cup confectioners’ sugar in a bowl until ribbons form; set aside. In the clean bowl of an electric mixer fitted with the whisk attachment, whisk egg whites until they reach soft peaks; add a scant 1/2 cup confectioners’ sugar and continue whisking until stiff peaks form.
Whisk in one-third of the yolk mixture into the egg white mixture; fold in remaining yolk mixture using a metal spoon until it is almost fully incorporated. Sift cocoa and potato flour into bowl; gently fold with a metal spoon until just combined.
Using an offset spatula, spread batter on prepared baking sheet to form a 10 1/2-by-12-inch rectangle, about 5/8 inch thick. Transfer to oven and bake until cake springs back when touched, 8 to 10 minutes.
Meanwhile, line a large wire rack with a clean dish towel. Turn cake out onto prepared rack and carefully peel off parchment paper. Let stand 5 minutes to cool.
Meanwhile, in the bowl of an electric mixer fitted with the whisk attachment, beat heavy cream with remaining 1/4 cup confectioners’ sugar until ribbons form; set aside.
Carefully transfer cake to a large piece of wax paper. Using a pastry brush, brush 1/4 cup coulis over cake; using a serrated knife, carefully trim edges from all four sides. Using an offset spatula, spread cream over cake, leaving a 5/8-inch border all around; top with raspberries. Starting from one of the long sides, gently roll up cake, using the wax paper to help you. Transfer cake to refrigerator and let chill 2 to 3 hours.
Slice roulade crosswise and serve dusted with confectioners’ sugar and drizzled with coulis.
