Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper.
Unroll the croissant dough and separate into triangles. Brush each triangle with melted butter.
Make the cookie dough: In a bowl, beat softened butter with both sugars until light and fluffy. Add the egg and vanilla and mix until smooth. Stir in flour, baking soda, and salt, then fold in chocolate chips.
Assemble the crookies: Place a spoonful of cookie dough on the wide end of each croissant triangle. Roll it up like a normal croissant, leaving some cookie dough exposed at the top if desired.
Bake for 15–20 minutes, until the croissants are golden and the cookie dough is just set.
Cool for 5–10 minutes before serving. Add toppings if using, and enjoy warm!
Notes
Chill the cookie dough for 15–30 minutes if you want it to hold its shape better during baking.
You can make both the cookie dough and croissant base ahead and store separately until ready to assemble.