Napoleon Cake

Method

1. On a lightly floured surface roll the 110 g of puff pastry into a rectangle about 3 mm thick and roughly 14 x 22 cm. Prick it all over with a fork, slide onto a lined baking tray and chill for 30 minutes so it will not shrink or dome.
2. Heat the oven to 200C. Lay a sheet of baking paper over the chilled pastry and set a second baking tray on top to weigh it down. Bake for 18 minutes, lift off the top tray and paper, and bake a further 4-6 minutes until deep golden, dry and evenly caramelised underneath. Cool completely on a rack, then trim with a serrated knife into 3 neat rectangles of about 10 x 4 cm.
3. Bring the 120 ml of milk to a bare simmer in a small pan with the 0.5 vanilla pod, seeds scraped in, and a pinch of salt. In a bowl whisk the 1 egg yolk with the 20 g of caster sugar until pale, then whisk in the 8 g of cornflour.