Mix well butter, sugar and vanilla pulp. Gradually add the eggs and a little salt.
Sift the flour and baking powder, mix and fold into the batter. Add the buttermilk and finally carefully fold in the blueberries.
Pour the batter into a greased or muffin tin and bake in a preheated oven at 180 °C top/bottom heat for approx. 30 minutes.