Roll the dough into a rectangle 8 by 14 in/20 by 36 cm.
Spread the jam over the dough, leaving bare a strip of dough 1 in/3 cm wide along one of the long sides.
Starting from the long side with the filling, roll up the dough into a roulade 14 in/36 cm long and press gently to seal. Using a sharp paring knife, cut three parallel lines down the length o