To make the caramelised white chocolate, heat the oven to 140C (120C fan)/275F/gas mark 1.

Put the chocolate on an oven tray, bake for 10 minutes, then stir until smooth.

Return the chocolate to the oven for a further 60-70 minutes, repeating the stirring process every 15 minutes.

Once the chocolate turns a light caramel colour, stir in a pinch of salt and leave to cool.

Meanwhile, line the base and sides of a 20 cm loose-bottomed cake tin and turn the oven up to 160C (140C fan)/325F/gas mark 3.

Finely crush the biscuits in a food processor.

Stir in the melted butter, then tip the biscuit mix into the lined tin and press it tightly into the base and up the sides.

Chill while you make the filling.

If the caramelised chocolate has set, melt it in the microwave, then leave to cool a little.

Put the cream cheese, sugar and a quarter-teaspoon of salt in a large bowl and mix until smooth.

Add the whole eggs and egg yolks, mix well, then stir in the soured cream.

Pour in the melted chocolate, stir until smooth, then pour into the tin.

Wrap the base and sides of the tin in two or three sheets of tinfoil, put it on a larger baking tray and pour in enough boiling water to come halfway up the sides of the cake tin.

Bake for 75-85 minutes, until the edges look set but there's a good wobble in the middle.

Remove the cheesecake from the water bath and leave to cool to room temperature.

Transfer to the fridge to chill for at least three hours.

Meanwhile, put the rhubarb in a wide, shallow pan with the sugar and vanilla, and macerate for 10 minutes.

Add 85 ml cold water, bring to a simmer and cook gently over a medium heat for three to five minutes, until the edges of the rhubarb start to soften but still hold their shape.

Leave to cool in the pan.

To serve, carefully unclip the cheesecake from its tin, top with the poached rhubarb and slice.