Heat oven to 350°F. Spray cookie sheet with cooking spray. In food processor bowl with metal blade, process ham and cream cheese until smooth and well blended.
If using crescent rolls: Unroll dough into 1 large rectangle; press into 13x8-inch rectangle, firmly pressing perforations to seal. If using dough sheet: Unroll dough; press into 13x8-inch rectangle.
Spread ham mixture over rectangle. Sprinkle with Parmesan cheese, Swiss cheese and onions.
Starting with both short sides of rectangle, roll up both toward center. With serrated knife, cut into 16 slices; place cut side down on cookie sheet.
Bake 13 to 17 minutes or until edges are golden brown. Immediately remove from cookie sheet. Serve warm.