HEAT THE MILK: Begin by heating the milk slightly in a small saucepan until it is just warm. Remove from the heat, add the butter to the pan and set aside.

KNEAD THE DOUGH: In the bowl of a stand mixer with the dough hook fitted, or a large mixing bowl, stir together 300g of flour, the sugar, sea salt and yeast until well combined. Add the milk, butter and egg yolk to the flour and yeast mixture, then knead on high-speed or stir vigorously until smooth.

FIRST RISE: Add all the remaining flour, then knead for 5 minutes until you have a smooth, pliable dough. Cover loosely with plastic wrap and allow to rise in a warm place for 1-2 hours, until doubled in size. Keep an eye on room temperature, dough takes longer to rise in a colder room.

SHAPE AND SECOND RISE: Line a baking tray with parchment paper and set aside. When the dough has doubled, lift it out of the bowl, weigh the dough, then divide into 8 equal pieces (weigh them for accuracy). On a clean work surface, using a circular motion, roll each piece of dough into a tight ball, pinching the edges to seal. Place on the prepared tray with the pinched side down. Make sure to leave plenty of space for the dough to expand. Cover with a clean tea towel and allow to rise for another 45 minutes to 1 hour.

BAKE: When the dough has nearly finished rising, heat the oven to 180°C / 350°F / Gas 4. When the dough has risen, whisk together the reserved egg white with the milk and use a pastry brush to brush the risen buns gently, but thoroughly with the mixture. Sprinkle sesame or poppy seeds over the top of each bun, then bake the buns in the preheated oven for 15 minutes, until well risen and golden brown.

COOL AND SERVE: Allow to cool on a wire rack before halving and loading with your favourite burger filling.