Begin by gently warming the milk until it’s lukewarm; not too hot to touch. Mix the warm milk with a tablespoon of granulated sugar, then sprinkle the active dry yeast over the top. Allow it to sit for about 5 minutes until foamy.

In a stand mixer, combine all-purpose flour and salt. Once the yeast mixture is frothy, add it along with eggs, softened butter, and vanilla extract to the flour. Mix on low speed until combined, then knead for 13-15 minutes.

Transfer the dough to a greased bowl, cover with a kitchen towel, and place it in a warm area to rise until it doubles in size, about 1 to 1.5 hours.

For the filling, melt chocolate chips, cocoa powder, sugar, butter, and salt in a double boiler. Stir until melted and smooth, then cool to room temperature.

Once the dough has risen, punch it down, roll it out into a 12 by 18 inches rectangle, spread the filling evenly, and roll it into a log. Slice it in half lengthwise and twist halves together.

Place the braided babka in a greased loaf pan, cover with a towel, and let it rise for 45 minutes to 1 hour.

Preheat the oven to 350°F (175°C). Whisk the egg for the wash and brush it generously on top of the babka.

Bake for 30-35 minutes until golden brown and hollow sounding when tapped.

Cool the babka in the pan for 10 minutes, then transfer to a wire rack to cool completely.