Preheat the oven to 400.

In a small bowl, combine ham, cheese and scallions and mix together.

On a flat surface, place an egg roll wrapper, corner facing toward you (like a diamond) and  put 3 slightly rounded tablespoons of ham mixture down the center of the wrapper, corner to corner, leaving ½ inch or so of space at the top and bottom. Fold one side of the wrapper in over the filling, followed by the top and bottom. Fold the remaining side in to completely cover filling and seal the loose end with a little bit of water. Repeat with remaining ingredients.

Spray a baking sheet with cooking spray and lay the egg rolls on the sheet. Coat the tops of the egg rolls lightly with cooking spray. Bake 16 minutes, flipping once, until the wrappers are golden brown. Serve with mustard for dipping.