Mix together the flour, salt, sugar, yeast and water in a mixing bowl to form a firm dough. Knead for 10 minutes by hand or 5 minutes in an electric mixer bowl using a dough hook.

Remove the butter from the fridge and warm very slightly so that it can be flattened out into a rough rectangle about 1-2cm thick.

Roll out the dough into a rectangle that is roughly a third larger than the size of the butter.

Place the butter on top of the dough, making sure it only covers two-thirds of it.

Fold the third of the dough that’s not covered by the butter over the butter-covered dough. You will be left with a third of the butter-covered dough exposed. Fold that back onto the dough, layering the dough and the butter.

Roll the butter and dough layers with a rolling pin to press them down. Cover and chill in the refrigerator for 15 minutes.

Take the dough butter mix out of the fridge, place the short end towards you and roll out the dough into a rectangular shape, approximately 15mm thick. Repeat the folding process, cover with cling-film and chill in the refrigerator for 15 minutes.

Repeat the folding and chilling process two more times so that you have rolled and folded 4 times. Wrap loosely in cling film and chill in the fridge for a couple of hours or overnight. Roll out the chilled dough to a large rectangle the thickness of a pound coin.

Cut the dough into 12 x 12cm squares.

Using a sharp knife, cut the chocolate into 12 lengths (don’t worry if it shatters a little). Arrange a row of chocolate along one edge of each piece of dough and roll the dough over forming a sausage.

Place the pain au chocolat on a baking sheet lined with greaseproof paper. Cover with oiled cling film and leave to prove for 1 hour.

Preheat the oven to 220°C (fan 200°C, gas mark 7). Bake the pain au chocolat for 15-20 minutes until risen and golden. Serve warm.