Preparation:

Working in a bowl the butter until creamy. Add the sugar and beat until the mixture is foamy and swollen. Add eggs, one at a time, vanilla, baking powder and salt. Ancher add the sifted flour alternating with the milk. Finally incorporate the blueberries and mix gently. Pour the mixture into the appropriate cups filled to 2/3 and transfer in a hot oven at 180 degrees for about 20 minutes.