Day 1: Melt 30g of the butter and set aside. In a bowl, add the flour, sourdough starter, salt, water, and melted butter. Start with 100ml of the water and mix it until it forms a ball. Add in the remaining 20 ml if necessary. Knead it for 4-5 minutes into a smooth ball then place it in an airtight container in the refrigerator for 8-20 hours.

Leave the remaining 200g of butter at room temperature ready for day 2.

Day 2: Take two sheets of baking paper and slice room temperature butter into 4 even slices. Lay the slices of butter in a square on one baking paper sheet. Place the second sheet of baking paper overtop. Using a rolling pin, roll the butter out into a 15 x 20cm (6"x8") rectangle. Alternatively, you can mix up the butter into a soft mixture and roll that out into a square.

Place the butter rectangle in the refrigerator for around 10 minutes to firm up slightly, but ensure it’s still a little pliable and not rock hard. If you're making the butter block in advance, take it out 15 minutes before you laminate the dough, to slightly soften. You want the butter and dough to be similar consistency.

Firstly, take the dough from the refrigerator and roll it out in front of you into a 20 x 30cm (8"x12") rectangle. Secondly, lay the cool butter on the dough on the bottom 2 thirds of the dough rectangle.

Fold over the top third, over the butter. Take the bottom third and fold that over like a pamphlet (the bottom third will be both dough and butter.)

The dough is now a horizontal rectangle. Turn it one-quarter turn clockwise so that it is now a vertical rectangle. Gently push with a rolling pin a few times along the length of the dough to help work in the butter. Roll the pastry out into another 20 x 30cm (8"x12") rectangle and fold it once again into a pamphlet. Turn the pamphlet 90 degrees and roll it out again into a 20 x 30cm (8"x12") rectangle, and fold it up into a pamphlet.

That was two turns and rolls in total. Now the folded dough needs to rest in the refrigerator for at least 30 minutes.

After 30 minutes remove it from the refrigerator and lay it out on the bench so it is a vertical rectangle.

Roll it out again into a 20 x 30cm (8"x12") rectangle and repeat the folding, and rolling to complete another two turns. Chill the dough for at least 30 minutes.

Repeat this process one more time, so in total the dough was turned and rolled a total of 6 times.

After all the turns are completed, let the dough chill for a minimum of 2 hours in the refrigerator before rolling it for baking.

The baking temperature and time will depend on the recipe you use the puff pastry in. Puff pastry does best in an initially hot oven of around 220°C/425°F regular oven or 200°C/392°F Fan-bake for the first 10-15 minutes to allow the pastry to puff up nice and big.

Afterward, the oven temperature can be lowered to allow the pastry to continue baking. How long it needs to be baked for depends on how it is being used.