Preheat oven to 160 °C. Grease and line a 20cm round cake tin.
Place butter, flour, sugar, eggs, baking powder and vanilla extract into a bowl and beat with a hand mixer for a few minutes until the mixture looks light and fluffy.
Add the vanilla quark and lime zest and beat the mixture for another 30 seconds. Stir through two handfuls of blueberries.
Pour the mixture into the cake tin and bake for 40 – 50 minutes.
To make the icing beat the cream cheese and icing sugar together until smooth. Add the lime zest and juice and stir through.
Once the cake has cooled spread the icing on top and sprinkle with the remaining blueberries.