Roll pastry out on parchment paper, into the shape of a square. Lay paper and pastry on a cookie sheet.
Sprinkle the coconut over the puff pastry, leaving a 1-inch border. Top with chocolate chips, reserving 1 tablespoon. Spread pecans over the chocolate and then add the last tablespoon of chocolate chips. Fold up the puff pastry around the tart.
Whisk together egg and water and use it to brush the crust before baking.