60g butter at room temperature
260g white chocolate, chopped
50g vegetable oil (e.g corn oil)
Melt chocolate in the microwave and allow to cool down to room temperature. Whip butter until pale and fluffy, then add white chocolate to the butter and whisk until smooth. Whisk in oil.
Chop blueberries into small chunks. Add to the chocolate mixture, pour spread into a jar and keep chilled.