Preheat the oven to 180°C. Grease and line a 20 cm cake tin.
Cream the butter and sugar until thick and light. Add one egg at a time, whisking well between each addition. Whisk in the vanilla.
Sift or aerate the dry ingredients – you can do this by whisking them together. Alternately fold the dry ingredients and milk into the butter mixture.
Coat the berries in a little flour, shaking off any excess flour. This prevents them from sinking to the bottom of the cake.
Gently fold the berries into the cake batter. Pour the batter into the prepared cake tin, smooth the top and reduce the oven temperature to 160°C. Bake for 60-80 minutes, or until a skewer comes out clean when tested.
Set aside to cool before removing from the tin.
Combine the mascarpone, cream cheese and icing sugar using a wooden spoon. Spread the icing over the cake, dribble over the passionfruit pulp and scatter over the blueberries. Serve cool or at room temperature.
Try cutting the quantity of berries to 300 g, or maybe just stick to blueberries, as the cake can get a bit too wet.