Black Forest Chocolate Roll Cake with Cherries and Cream

Make the cherry filling first so it can cool: stir the cherries, sugar, cornstarch and water in a small saucepan over medium heat until the mixture boils and turns thick and glossy, 3 to 5 minutes. Stir in the kirsch, if using, and let it cool completely.

Heat the oven to 350°F (175°C) and line a 10 x 15-inch (25 x 38 cm) jelly roll pan with parchment paper. Sift the flour, cocoa, baking powder and salt together.

Beat the egg yolks with half of the sugar until thick and pale, then mix in the vanilla and milk. In a clean bowl, whip the egg whites to soft peaks, then gradually add the remaining sugar and beat until stiff and glossy.

Fold the dry ingredients into the yolk mixture, then fold in the egg whites in three additions, gently, so the batter stays airy. Spread it evenly in the pan.

Bake for 10 to 12 minutes, until the top springs back when lightly pressed. Immediately turn the sponge out onto a clean kitchen towel dusted with powdered sugar, peel off the parchment and roll it up from a short end with the towel inside. Let it cool completely.

Whip the cream with the powdered sugar and vanilla until it holds stiff peaks.

Unroll the sponge and spread it with about two-thirds of the cream, then spoon the cherry filling over it. Roll it back up firmly without the towel and set it seam-side down on a platter.

Cover the outside with the remaining cream, decorate with chocolate shavings, whole cherries and a dusting of powdered sugar, and chill for at least 1 hour before slicing.