Sourdough Cinnamon Roll Christmas Tree Pull Apart

Warm the milk to around 37C. Add the warm milk and sugar to a bowl and whisk until sugar is dissolved.
Now add your egg yolks and sourdough starter to the mixture and whisk until they are well beaten and blended through the milk and sugar.
To this add your flour and salt and bring together into a rough dough. Allow the dough to sit, covered at room temperature, for around half an hour.
Now, tip the shaggy dough out onto the counter and knead it a little.
Add the butter, little by little, kneading it into the dough until all the butter has been used up (see notes for using a stand mixer for this if you prefer not to do it by hand).
The dough should be fairly soft and elastic, but not sticky.
Transfer to the dough to a bowl and allow to ferment, covered with some plastic wrap or elastic food cover.. You want the dough to rise a little (around 30%) and feel soft to the touch. This needs to happen at room temp - not in the fridge.
Once the dough has finished bulk ferment, you will need to fill and shape the cinnamon rolls.

Before you roll out the dough, take the egg and milk and whisk together to create an egg wash. Set this aside.
In a small bowl, combine the brown sugar, cinnamon and flour and mix together until it resembles beach sand (it's quite dry and that's ok).
Turn the dough out on to the counter. It shouldn't be sticky and be easy the handle. Do not use flour when rolling out the dough.
Divide the dough into two pieces and roll each one out into a rectangle (around 30cm long by 15cm wide).
Using a pastry brush, brush egg wash onto the whole surface of the dough rectangles.
Now spread the filling all over the dough, leaving a 2cm gap on one of the long edges. You need to leave a gap so that dough will stick to itself when you roll it.
Once the filling is spread, roll the dough into a log, starting on the opposite long edge to the gap you've left.
Roll the dough into a tight log, using the unfilled dough to seal the log.
Lay the log out with the seam underneath.
Cut each log into approximately 10 cinnamon rolls. A metal dough scraper is perfect for this.
Take a cookie sheet that has been lined with parchment paper and arrange the sourdough cinnamon rolls into the shape of a Christmas tree. Try to get the seams of each cinnamon roll facing inwards so that they don't come undone when they are baked.
Gently press the rolls down with your fingers to fill the Christmas tree shape out.

Cover the tray with a damp kitchen towel and leave the sourdough cinnamon rolls to proof. You want them to be nice and puffy before you bake them.
Once the dough is puffy, you can bake them straight away - or see baking timeline above to extend the second rise and hold them in the fridge overnight.

Once the rolls are puffy, it's time to bake them. Preheat your oven to 180C/356F.
Bake rolls for 30 minutes at 180C/356F. Keep an eye on them though as they will burn easily due to the sugar.
Once they're finished baking, leave them to cool on the tray for around 10 minutes before transferring them to a platter or cooling rack.
You can brush them with butter to give them a nice glaze. You can leave them unbuttered if you prefer. The butter will give them a nice shine.

Add cream cheese, butter, powdered sugar, vanilla and salt to a mixing bowl and beat the frosting until it's thick and glossy (you can use a whisk or spatula). Alternatively you can use a stand mixer to make the frosting. Store in the fridge until ready to use.
Once the rolls have cooled a little (I leave it about 30 minutes) smother them in the vanilla cream cheese frosting. You can use a vanilla glaze or even just dust them in icing sugar if you prefer.
For the photos you can see in this recipe, I've used a piping bag with a star tip.