To make the preferment, mix the flour with the yeast and 200g room temperature water in a small bowl. Cover the bowl and leave to ferment for 12-24 hrs. Don’t worry about it bubbling up and coming down again – this is just about creating flavour.

For the dough, tip the preferment into a large bowl and pour over 225g tepid water. Stir with a spatula to combine. Tip in the flour and the rest of the yeast and mix everything together to make a rough dough. Make sure all the flour is mixed in and that there are no dry bits on the side of the bowl. Cover and leave to rest for at least 30 mins or up to 1 hr.

Scatter the fine salt over the dough, dip a hand into water and scrunch the salt through the dough to mix it in completely. Cover again and leave for 20-30 mins.

Wet your hands, grab the dough from one side and stretch it back over itself. Repeat with the other side – it should be very elastic. Curl the dough around itself so that it’s smooth and taught, then cover and leave for another 20-30 mins. Repeat this process twice more, then cover and leave to prove for 2-3 hrs until risen by about 40 per cent – the dough should be bubbly and soft.

Drizzle a deep, roughly 20 x 30cm baking tray with 2 tbsp of the olive oil and scrape the dough onto the tray. Incorporate the oil into the dough by stretching and folding it on the tray. Don’t worry if it’s a bit stringy to start, keep stretching and bringing it back on itself. When the dough has come together and is oily, cover and leave to prove at room temperature for 2 hrs, or for a much better flavour, up to 48 hrs in the fridge. Remove from the fridge 1 hr before baking.

Heat the oven to 230C/210C fan/gas 7. Meanwhile, cut the top off the head of garlic to expose the cloves. Sit the garlic on a piece of foil, drizzle with 1 tsp of the olive oil and season with salt. Wrap the bulb in the foil to create a parcel, put on a tray and roast for 25 mins. Remove from the oven and leave until cool enough to handle, then slip the garlic cloves out from their skins – they don’t need to be completely soft at this point.

Use your fingers to stretch the dough so it fits into the tray evenly, then dimple the surface using your fingertips. Push the garlic cloves and rosemary leaves deeply into the dough, evenly spaced apart. Drizzle with 1 tbsp olive oil and dimple a few more times to create oil puddles on the surface. Scatter over the 1 tsp sea salt flakes, give the dough a final poke and bake for 25-30 mins until puffed up and deep golden. Remove from the oven, drizzle with the remaining olive oil then leave to cool for at least 40 mins before cutting and serving. Best eaten straightaway, but will keep for two days in an airtight container.