Mix sourdough starter, flour, and water in a small bowl until well combined. Then tip it into a clean jar to rise. Let this rise overnight until doubled in size.*

In the bowl of a stand mixer fitted with a dough hook attachment, combine milk, sugar, sourdough starter, egg, flour and salt. Mix into a thick and slightly sticky dough.

Add in the softened butter and mix again for around 10-15 minutes on medium speed until the dough is silky and strong and passes the window pane test.

Shape into a ball and place in a container with a lid, or a bowl and cover it.

Let the dough rise in a warm spot (ideally around 25°C/77°F) for anywhere from 5-8 hours depending on temperature until it's bulked out by at least 50%. You can create a warm and humid spot by placing the dough into a turned-off oven alongside a dish of boiled water. Replace the water as needed when it cools down.

After this rise, ensure the dough is covered tightly and refrigerate overnight.

The following day, remove from the fridge and let it come to room temperature for 15 minutes. Meanwhile, mix together the softened butter, herbs, garlic and salt for the filling.

Line a 9x5 inch loaf pan with parchment paper.

Pull the dough onto a lightly floured surface and form it into a 12-inch (30cm) long log and cut it into 12 equal 1-inch pieces with a bench scraper or knife. If you want them even, weigh the whole dough first and divide it by 12.

Shape each piece into a little ball. Roll each ball into a circle around 4 ½ inches (11cm) in diameter.

Spread each piece with garlic butter, leaving a little border around. Add a sprinkle of cheese, then fold the dough circle in half.

Place the half circle into the loaf pan with the edges facing up. Continue with the remaining dough and filling, stacking the layers of dough. They will need to be squished in.

Cover the pan and let the dough rise again in a warm spot until doubled in size, around 4-6 hours depending on temperature.

Preheat the oven to 180°C (350°F). Whisk together egg and water for the egg wash and use a brush to brush this all over the top of the bread.

Bake for around 40-50 minutes until deep golden brown. If the top of the berad is browning too fast, loosely cover with a sheet of aluminum foil. After baking, brush the hot bread with melted butter and sprinkle a bit of flaky salt.

Leftover sourdough pull apart bread can be stored in an airtight container for up to 3 days. After day 1, reheat it in the microwave before eating to soften it up, as the enriched bread will stiffen on the following days.