1. **Prepare the Croissant Dough:**

– In a bowl, combine the flour and salt. Add the cold butter and work it into the flour until the mixture resembles coarse crumbs.

– Gradually mix in the cold water until a dough forms. Knead lightly, cover, and refrigerate for at least 30 minutes.

2. **Prepare the Cookie Dough:**

– In a separate bowl, cream the softened butter with the brown sugar and granulated sugar until smooth and fluffy.

– Beat in the egg and vanilla extract.

– Sift in the flour, baking soda, and salt; fold until just combined. Stir in the chocolate chips. Refrigerate the cookie dough for 15 minutes.

3. **Assemble the Cookie Croissant:**

– Preheat your oven to 375°F (190°C).

– Roll out the croissant dough on a lightly floured surface into a rectangle (approximately 12×8 inches).

– Place dollops of the cookie dough along one of the long edges of the dough.

– Gently roll the dough from the cookie-dough edge into a crescent shape, encasing the cookie dough inside.

– Transfer the roll to a baking sheet lined with parchment paper and brush lightly with the beaten egg.

4. **Bake:**

– Bake in the preheated oven for 15-20 minutes, or until the croissant is puffed up and golden brown and the cookie filling is set.

5. **Cool and Serve:**

– Allow the Cookie Croissant to cool slightly before serving. Enjoy warm for the best texture contrast between the flaky pastry and soft cookie center.