- Preheat oven to 180 degrees.
- Put all measured ingredients in a large mixing bowl and mix together using either an electric whisk or by hand, until pale and creamy. The mixture should be quite thick.
- Spoon 1/2 into a prepared, lined loaf tin and scatter over half the blueberries.
- Cover with a bit more cake mix and scatter more blueberries over then cover with the rest of the cake mix.
- Bake in the preheated oven for an hour or until a skewer comes out clean.
- Cool on wire rack and serve.