Preheat the oven to 160°C, fan 140°C, gas 3. Place the blackberries and 1 tbsp water in a medium saucepan with 1 tbsp of the sugar and cook for 5 mins until you have a syrupy sauce and the blackberries are slightly tender. Spoon into a 1 litre baking dish.
Place the egg yolks, remaining sugar, vanilla extract and whipping cream in a blender and whizz until smooth. Pour over the blackberries – do this by pouring over a spoon to ensure it drops down gently, so the custard doesn’t get mixed up with the berries. Place in a roasting tin and pour nearly boiling water into the tin until it comes halfway up the side of the dish.
Bake for 30 mins in the oven until the custard is set. Set aside to cool and serve either at room temperature or, if you have time, it is equally delicious chilled in the fridge for a few hours before serving.
Cook's tip: this can also be made using 150g frozen Black Forest fruits. Place in a saucepan while still frozen, without water, and cook as per step 1 of the recipe. You could also try other seasonal soft fruits such as plums and pears.