In a mixing bowl, combine all the dry ingredients for the dough. Add in the milk, butter and beaten egg and knead until a smooth dough is formed. Let it rise for 1-1.5 hours, or until it doubles in size.
Roll out your dough on a flour-dusted surface, aiming for a rectangle of about 12x16 inches.
To make the filling, melt your chocolate chips and butter together, then add in the sugar and cocoa powder. Spread it evenly over your rolled dough.
Starting from the short end of the rectangle, roll the dough up tightly. Slice the roll in half lengthways, turning the cut sides upward.
Twist the halves together, then place the loaf into a buttered, parchment-lined loaf pan. Let it rise for 30 minutes.
Preheat your oven to 375°F (190°C). Bake your babka for 45-55 minutes.
While it’s baking, prepare the syrup by combining water and sugar in a small saucepan, boiling until the sugar is dissolved.
When your babka is out of the oven and still hot, brush it with the sugar syrup for a glossy finish.