1Heat oven to 350°F. Grease bottom only of 13x9-inch pan with shortening or cooking spray. Make and bake cake mix as directed on box for 13x9-inch pan, using water, oil and eggs. Cool 10 minutes. Run knife around sides of pan to loosen cake; remove from pan to cooling rack. Cool completely, about 1 hour.
2Line cookie sheet with waxed paper. Crumble cake into large bowl. Add frosting; mix well with spoon. Shape mixture into 1-inch balls. Place on cookie sheet. Freeze at least 15 minutes or until firm.
3Meanwhile, in medium microwavable bowl, microwave chocolate chips uncovered on High 1 to 2 minutes, stirring every 30 seconds, until softened and chips can be stirred smooth. Dip half to three-quarters of each strawberry in melted chocolate; place on waxed paper. Repeat with marshmallows. Place 1 cake ball on fork; dip cake ball in melted chocolate to cover. Gently tap off excess. Return to cookie sheet. Repeat with remaining cake balls. Let dipped strawberries, marshmallows and cake balls stand until set.
4Cut each shortcake roll into 6 pieces. On each skewer, carefully thread 1 cake ball, 1 strawberry, 1 marshmallow and 1 shortcake roll piece. Serve or store in cool place until serving time. For longer storage and for a crunchy outer chocolate shell, refrigerate kabobs.