Start by adding the warm water to the bowl of your stand mixer. Take its temperature to be sure that it is less than 110F. If it is warmer, you risk damaging the wild yeast in your starter. Add in the active sourdough starter, sugar, salt, and egg then mix until well combined.

Add in the flour and mix on low speed until all flour is absorbed and the dough is just starting to come together. It will not be smooth at this point. Cover and let it rest for 20 minutes.

Turn your mixer back on and slowly add in the butter. Continue mixing until the dough is smooth and passes the window pane test. This may take up to 15 minutes.

Cover your dough and let rest for 4-6 hours or until it is finished bulk fermenting. How long this takes depends on the temperature of your dough. Warm dough will ferment faster than cool dough.

Divide your dough into 15 equal pieces, roughly 75g each, and shape them into a ball. I often pre-shape them all then go back and do a final shape before placing them into a greased glass casserole dish.

Cover your tray of dough balls and leave to proof. This can be done at room temperature or in the fridge. Remember that warm dough ferments faster than cool dough so it will only take another few hours at room temperature compared to 12-24 hours in the fridge. Feel free to do a combination of both to make it work for your schedule.

You'll know your buns are ready to bake when they have doubled in size and pass the poke test. If you're not sure, wait a little longer. Over proofed buns are much better than under proofed buns!

Bake at 350F for 25-30 minutes or until they are golden brown and have an internal temperature of at least 200F.

To keep your buns soft, brush the tops with butter while they are still hot and fresh from the oven.