Sift 150 g plain flour and 50 g Dutch-processed cocoa powder into a large mixing bowl. Add 80 g salted butter and rub it into the mixture until it resembles breadcrumbs. Add 1 medium egg yolk and mix well. Gradually add 4 tablespoons water or milk until the pastry comes together in a ball. Wrap in reusable wraps and chill for a minimum of one hour.

Remove the pastry from the fridge, flour your work surface, and roll the pastry out to just over nine inches in diameter. Place into a nine inch fluted tart tin, pushing it into the sides. Prick the surface and chill for a minimum of 30 minutes.

Preheat your oven to 180℃ (356℉). Cover the pastry with parchment paper and place ceramic baking beans on top. Blind bake for 20 minutes, then leave to cool.

Wash 300 g blackberries. Add the berries to a saucepan with 2 tablespoons granulated sugar and cook on medium-high until it boils and reduces. Cool and strain through a sieve.

In a stand mixer bowl, add 100 ml double cream, 250 g mascarpone, 150 g cottage cheese, 60 g icing sugar, and ¼ teaspoon Madagascan vanilla extract. Whisk until soft peaks form. Fold in the blackberry syrup.

Remove baking beans and parchment from the cooled pastry. Spoon in the blackberry mascarpone filling and level the surface. Optionally decorate with extra blackberries, chocolate, and edible flowers. For the best texture, chill overnight.