In a big bowl, mix together 390g White Bread Flour, 7g Instant Dry Yeast, 15g Sugar, 3g Salt, and set aside
In a small saucepan, melt 45g of Unsalted Butter, then add 180g of Milk and 90g water and warm gently. Once it has reached a temperature where it feels neither hot or cold to the touch, remove it from the heat and pour it into the mixing bowl with the dry ingredients
Fully combine these dry and wet components, then turn out onto a lightly floured surface and knead for a solid 10 minutes. If you are lucky enough to own a machine with a dough mixing function, use that instead After kneading the dough, place it back into the mixing bowl. Grease both the surface of the dough and the rim of the bowl with 15g of olive oil, then cover the bowl with plastic wrap
Leave the whole thing somewhere relatively warm to rise, until it has doubled in size. See our extra notes on rising and kneading Once risen, remove the dough from the bowl, and knock all of the air out of it before kneading it for a further 2-3 minutes
Next, take a sharp knife and divide the dough into roughly 6 equal parts, and roll each into a passable spheres, dusting each one with a little flour as you go
Place the dough balls on a grease-proof paper lined baking tray, leaving a generous gap between each one. Then, loosely cover the whole thing with plastic wrap, and once again, put them somewhere warm to rise
When the buns have risen to approximately one and a half times their size, pre-heat the oven to 180°C (350°F, Fan 160°C, Gas Mark 4)
When the oven has finished heating up, whisk one Egg Yolk in a small bowl
Remove the plastic wrap from the buns, don't worry if they don't look big enough, they will finish rising in the oven. Then, using a pastry brush, lightly cover the top of each one with Egg Yolk, before evenly distributing 8g of Sesame Seeds on top
Bake in the oven for approximately 20 minutes, until the buns are golden brown
Leave to cool, before constructing you very own ultimate hamburger!