1. Preheat oven at 180º (fan forced at 170ºC). Line a rectangular cake pan (approx 28cm x 18cm x 5cm) with baking paper.
2. Cream butter, sugar, vanilla and rind together until light and fluffy. Beat in eggs one at a time. Transfer to a bowl. Sift flour and baking powder together and stir half into creamed mixture then fold in yoghurt and remaining flour (don’t worry if mixture curdles slightly). Finally fold in frozen blueberries.
3. Spoon mixture into pan and bake on the middle shelf for 30-40 minutes or until cooked. Cool for 5 minutes before turning out onto a wire rack.

*Available from Kosher section of supermarket
** reduced sugar boysenberry yoghurt is great

VARIATION:
Use Creative Gourmet frozen Mixed Berries (halve blackberries), Raspberries or Cranberries instead of Blueberries.