250g self-raising flour
50g light muscovado sugar
125g unsalted butter, frozen
1 egg yolk
1 tsp vanilla extract
1 jar good-quality raspberry jam
For the vanilla custard
4 egg yolks
30g golden caster sugar
1 tsp cornflour
300ml double cream
1 vanilla pod, split lengthwise
Preheat the oven to 180°C/fan 160°C/gas mark 4 and place a roasting tin filled with hot water into the bottom of the oven to create some steam whilst cooking the roly poly.
Into a large bowl, sieve the flour and add the sugar. Grate the frozen butter into the flour and stir to mix. Make a well and add the egg yolk, milk and vanilla extract. Mix the ingredients together until you get a sticky dough.
Spread the dough evenly on a greased and lined baking tray, then spread the raspberry jam over the dough.
Roll the dough towards you to make a roulade, then wrap loosely in the baking paper. Wrap the roll loosely in kitchen foil (as the roly poly will puff up during cooking) and seal the edges of the foil.
Sit on the baking sheet and place in the oven for 50-60 minutes until cooked through. Remove and leave to cool.
To make the custard, in a bowl beat the egg yolks, sugar and cornflour. Whisk until well combined. In a saucepan, heat the cream with the vanilla pod. Once the cream has come to the boil, slowly pour over the egg yolk mixture whisking all the time.
Pour the mixture back into the saucepan and heat gently until it thickens enough to coat the back of a spoon. Pass through a sieve into a jug ready to serve.
Cut the roly poly into slices and serve with the vanilla custard.