DAY 1

Feed The Starter:

• First thing in the morning, feed your sourdough starter in the ratio of 1:1:1 and leave it in a warm spot for 4-5 hours to at least double in volume.

Make The Dough:

• When your sourdough starter is active and bubbly, start making the dough. In the bowl of a stand mixer, combine strong flour, sugar and salt. Add the sourdough starter, milk and egg. Mix the dough in your stand mixer, fitted with a dough hook attachment for 4-5 minutes until combined (it does not have to be smooth and elastic at this point). Cover the bowl, and leave the dough to rest for 10 minutes.
• Run the mixer on low speed again, and bit by bit, add the softened butter. Increase the mixer to medium speed and keep on kneading for about 10 minutes, or until the dough passes the windowpane test (until you can stretch the dough so thin that you can see through it without tearing it). The dough will be soft and elastic, but a little less sticky than brioche dough.

Bulk Fermentation and Cold Ferment:

• Tip the dough onto a work surface, shape it into a ball and place it into a large lightly oiled bowl. Cover it with plastic wrap and leave it in a warm place to finish bulk fermentation for 4-5 hours, until it almost doubles in volume.
• Transfer the bowl to the fridge and leave it to cold ferment overnight (8-16 hours).

DAY 2

Shaping and Filling

• In a small bowl, combine softened unsalted butter, minced garlic, finely chopped parsley and salt.
• Grease a 24x24cm baking dish with butter (alternatively, line the baking tray with a sheet of parchment paper). You will want a dish with high rims so that you can cover the top without the top of the dough touching the cover as the rolls rise.
• Scoop the dough out of the bowl onto a lightly floured surface. It should be quite firm and not sticky. Using a stainless steel rolling pin (or a floured rolling pin), roll the dough out into a rectangle measuring approx. 42x30cm.
• Spread the garlic butter on top. Scatter the parmesan and mozzarella all over.
• Roll it into a tight log and pinch the seam together, then cut it into 9 even pieces. Alternatively, cut the rolled out dough into 9 even long strips, about 4.5 cm (1¾ in). Roll each strip tightly and arrange them in a prepared baking dish.

Second Proof

• Cover your unbaked rolls with a lightly oiled cling film and leave the sourdough cheese rolls for 4-5 hours for their final rise. Choose a warm spot (22-25°C is ideal). If your kitchen is colder, you may need to leave them to rise for longer. Your buns should have bulked up by about 75% when they are ready to bake. Read more about how to know when sourdough is ready to bake.
• Preheat the oven to 180°C (360°F).

Baking

• Scatter the mozzarella and parmesan on top and place the rolls in the centre of the oven for approx 25-30 minutes, until they are golden brown.

Garlic Butter Finish

• In the meantime, prepare the garlic butter, by placing butter and minced garlic in a small saucepan. Allow the butter to melt and gently bubble over very low heat for 5-8 minutes, until garlic softens and butter infuses, but do not allow the garlic to brown. Take it off heat and stir in salt and parsley.
• Once baked, remove the rolls from the oven and brush the garlic butter all over the surface. Leave them to cool down in the tray for 15-20 minutes, and serve warm!