Preheat oven to 180°C (350°F).
In a bowl, mix melted butter, brown sugar, and white sugar until smooth.
Add the egg and vanilla extract, mixing until combined.
Stir in the flour, baking soda, baking powder, and salt. Fold in the chocolate chips.
Carefully split the croissant in half, stuff the bottom half with cookie dough, and place more cookie dough on top of the croissant.
Bake for 18 minutes or until golden. Enjoy warm!