Ricotta and orange cake

Preheat the oven to 180°C/gas 4.

Grease a springform tin with butter. Sprinkle the base and sides with the 2 tablespoons of vanilla sugar.

Put the raisins in a small saucepan with the orange juice and liqueur. Simmer gently until the raisins are plump. Remove from the heat and leave to cool.

Cream together the butter and sugar until smooth and fluffy. Gradually beat in the eggs with the potato flour and baking powder.

Using a metal spoon, fold in the orange and lemon zest, the orange flower water and the orange oil, if using.

Push the ricotta through a food mill or coarse sieve, stirring it into the mixture as you go.

Finally stir in the plumped up raisins.

Spoon the mixture into the prepared tin. Bake in the centre of the oven for 55 minutes until firm.