Beat together the butter, ⅔ cup Tatua Cream Cheese and sugar until light and fluffy. Add the eggs one at a time, followed by the egg white. Add the vanilla and mix well.
In a small bowl, fold together the boysenberries and 2 Tbsp of flour. Set aside.
Sieve and mix together the remaining dry ingredients. Whisk in half of the dry ingredients, followed by half of the Tatua Sour Cream. Repeat. Gently fold in the boysenberries until just mixed through.
Transfer to a greased bundt or loaf tin. Bake the cake for 50-60 minutes or until the cake is golden and a toothpick comes out clean when tested. Leave to cool for 30 minutes, then tip out onto a cooling rack.
In a bowl, mix together the remaining Tatua Cream Cheese, icing sugar and remaining vanilla. Spread over the cake while warm and leave to settle into the cake.