Combine ham, cheese and scallion in a small bowl; mix well.
Place an egg roll wrapper on a flat work surface with the corners set vertically (pointing up and down – like a diamond shape). Arrange 3 slightly rounded tablespoons of filling down the center of the wrapper, leaving 1/2 inch of space at the bottom and top.
Fold the bottom of the wrapper to the center, over the filling. Gently, but firmly, fold the left side of the wrapper to the center and then fold in the right side. Fold the top of the wrapper down to cover filling and seal any loose ends with water; repeat with remaining ingredients.
Place filled wrappers on prepared baking sheet; lightly coat surface of wrappers with cooking spray. Bake until wrappers are golden brown, flipping once, about 15 minutes.
Yields 1 egg roll and 1 1/2 teaspoons of honey mustard per serving.