In the bowl of your mixer, add warm milk, granulated sugar, cream, yeast and sourdough starter
Stir until the sugar dissolves and everything is evenly mixed
Add both flours and the salt. Mix on low for 3 minutes and medium speed for 3 minutes
Go back to low speed and add the butter progressively
Continue kneading for 6-10 minutes more until smooth and the butter fully incorporated
Place the dough in a lightly oiled bowl, cover, and let rise in a warm spot (25–28 °C) for 1 ¼ - 1 ½ hours until doubled
Roll the dough into a 60 × 40 cm rectangle
Spread the custard evenly over the dough
Repeat with the chocolate chips
Fold the dough twice like an envelope
Slice into 8–10 strips (approximately 3 cm wide)
Twist each strip several times and shape into a roll
Place on baking paper lined trays and let rise in a warm place (24–26 °C) for 40–60 minutes until puffy
Preheat your oven to 200°C
Egg wash the buns
Bake for 13-15 minutes until golden brown
Optional: brush with syrup made from 2 tbsp sugar mixed with 2 tbsp boiling water
