Crab rangoon filling: add cream cheese, crab, and the thinly sliced whites of scallions to a large bowl and stir to combine well. This is your crab rangoon filling, and you can store it in the refrigerator until time to use or for no more than 4 or 5 days. 

Assembly: line a sheet pan with parchment and add some water to a small bowl.

To fill each wonton, scoop 1 tablespoon of filling onto a wonton, wet your finger with water, and moisten all of the edges of the wonton. Then pinch all the corners together at the top. Then make sure all the sides that are touching are sealed, and repeat until you are out of filling. 

Place each crab rangoon on a parchment-lined sheet pan spaced out at least an inch apart. Spray all of the crab rangoon lightly with cooking spray, which should help them brown in the oven.

Bake at 400°F (200°C) for 15 to 20 minutes. If you have a convection setting on your oven, this will help the wontons get crispier. 

Allow the crab rangoon to cool and then serve with duck sauce or sweet and sour sauce.