An hour before you begin, remove all the ingredients from the fridge and bring to room temperature. Line the base of a 23cm springform cake tin, 7cm deep, with baking parchment. Melt the white chocolate in a heatproof bowl in the microwave for 1 min, stirring halfway through. If necessary, put back in for further 10-second bursts until the chocolate is melted. Alternatively, melt the chocolate in a heatproof bowl over a pan of just simmering water, ensuring the bottom of the bowl doesn’t meet the water. Leave to cool while you make the base.
