Blackberry Yogurt Cake - cooking recipe

Ingredients

3 None eggs, separated
3/4 cup butter
1 cup granulated sugar
2 cups full-fat yogurt
1 1/4 cups all-purpose flour
3/4 tsp baking powder
1/2 lb blackberries
5 sheets gelatin or 1 1/2 tbsp powdered gelatin, soaked in cold water
1 cup heavy cream, whipped to stiff peaks
2 tbsp pistachios, chopped

Preparation

Preheat the oven to 325\u00b0F. Grease a 13 x 15 inch rimmed baking tray and sprinkle with flour. Whip the egg whites and a pinch of salt to stiff peaks. Chill.
Meanwhile, cream the butter and 3/4 cup sugar. Beat in the egg yolks, 1 at a time. Stir in 1/3 cup yogurt. Fold in the flour and baking powder. Gently fold in the egg whites in 3 batches. Transfer to the prepared tray and smooth out. Bake for 20 mins, until a skewer comes out clean. Allow to cool.
For the blackberry yogurt, puree 1/4 lb blackberries with 2 tbsp sugar. Squeeze out any excess water if using sheet gelatin and melt in a saucepan over low heat with 1/4 cup yogurt. Stir into the remaining yogurt along with 2 tbsp sugar. Gently fold in the whipped cream. Divide the mixture in 1/2 and fold the pureed berries into 1/2. Spread the blackberry cream over the sponge cake then spread the remaining cream over top. Swirl a fork through both to form a marbled effect. Press the remaining blackberries into the top and chill for 2 hours.
To serve, cut the cake into 12 squares and sprinkle with the pistachios.