Prepare popcorn according to package directions.  Remove all unpopped kernels.  Place popped corn in large bowl sprayed with cooking spray.

Spray sides only of medium-sized heavy saucepan with cooking spray.  Combine confectioners’ sugar, marshmallows, corn syrup, Fleischmann’s, cold water and salt, if desired, in saucepan over medium-high heat.  Stir constantly with wooden spoon until mixture comes to a boil. Remove from heat; pour over popcorn, stirring gently until evenly coated.

Spray hands with cooking spray and quickly shape popcorn mixture into 1-1/2-inch balls. Allow to cool before eating.  Store in airtight container.