Repeat with the other rectangles. Bake for ten minutes, or until lightly golden-brown and puffed up. Leave to cool before making the crème fraîche filling and adding your choice of topping(s).

So, how does it miraculously puff up to such great heights? It’s all thanks to steam. In the oven, the moisture in the dough creates pockets of steam which puff up in layers between pockets of fat.