First things first, preheat your oven to 200C/180C Fan/Gas 6. Pop a roasting tray ½ filled with water in the bottom of the oven – this creates steam and helps your jam roly poly bake. Butter a large sheet of baking paper and set aside for later.
Stir the flour and Baking Powder into a large bowl, add the sugar and stir until fully combined. Add the butter and rub into the flour mix. Stir through the suet. Finally pour in ½ the milk and Vanilla Paste and stir to form a dough, slowly add the remaining milk, stirring until you have a soft, spongy dough.
Pop your dough out onto a floured surface and briefly knead until you have a smooth dough. Roll the dough out to a rectangle approx. 20cm x 30cm. Spread the jam onto the dough, leaving a 1.5cm border. Gently roll the dough up from the short end.
Gently transfer to your prepared greaseproof paper and place seam-side down. Loosely wrap the roly poly in the baking paper, leaving plenty of room for the pudding to expand as it bakes. Twist the ends of the paper like a Christmas cracker and tie tightly with string. Then repeat wrapping in foil and securing the ends in string.
Place the pudding onto baking tray and pop into the oven in the shelf above the roasting tin with water and leave to bake for 30-35 minutes. The pudding should be well risen and lightly golden. Don’t worry if the jam has leaked out in some places it will still taste delicious.
Unwrap your pudding and put on a serving plate and cut into slices. Serve warm with custard or cream.