1. Preheat your oven to 375 F (190 C). Lightly flour a clean work surface. Unroll the crescent roll dough onto the floured surface, pressing the seams together firmly to form a single rectangular sheet. If there are perforations, make sure they are completely sealed.

2. In a small microwave-safe bowl, combine the dark chocolate chips and melted butter. Microwave in 15-second intervals, stirring after each, until the chocolate is mostly melted and smooth. Stir in the granulated sugar, vanilla extract, and pinch of salt until well combined. The mixture should be thick and spreadable.

3. Using an offset spatula or the back of a spoon, evenly spread the chocolate filling over the entire surface of the crescent roll dough, leaving a small border (about 1/2 inch) around the edges. This helps prevent the filling from oozing out too much during rolling.

4. Starting from one of the longer sides, carefully roll the dough tightly into a log. Once rolled, use a sharp knife to carefully slice the log lengthwise down the middle, creating two long halves with the chocolate swirl exposed.

5. Lay the two halves next to each other, cut-side up. Gently cross one half over the other, forming an “X.” Continue to twist and braid the two pieces together, keeping the cut sides facing up as much as possible to showcase the layers. Pinch the ends together to seal.

6. Carefully transfer the braided babka to a parchment paper-lined baking sheet. In a small bowl, whisk together the beaten egg and milk to create an egg wash. Brush the entire surface of the babka with the egg wash. This will give it a beautiful golden-brown crust.

7. Bake for 20-25 minutes, or until the babka is golden brown and the chocolate filling is bubbly. Keep an eye on it to prevent over-browning. If it starts to get too dark, you can loosely tent it with aluminum foil.

8. Once baked, remove the babka from the oven and let it cool on the baking sheet for about 10-15 minutes before transferring it to a wire rack to cool completely. Dust with powdered sugar, if desired, before slicing and serving.