1Heat oven to 350°F. Make and bake cake mix as directed on box for 13x9-inch pan, using water, oil and eggs. Cool completely, about 1 hour.
2Line cookie sheet with waxed paper. Crumble cake into large bowl. Add frosting and 1/2 cup of the chopped candied pecans; mix until mixture holds together. Shape into 8 (2-inch) balls; place on cookie sheet. Freeze about 30 minutes. Fill ice cream cones with remaining cake mixture; set aside.
3In small microwavable bowl, microwave candy melts on High 1 to2 minutes, stirring once, until smooth. Remove cake balls from freezer. Dip bottom of 1 cake ball in melted candy; place on ice cream cone. Press gently to adhere. Stand in ice cream cone holder. (If holder is unavailable, tightly cover top of empty rectangular pan, at least 2 1/2 inches deep, with heavy-duty foil. Cut 8 slits, 1 inch long and 3 inches apart, in foil.) Let stand until set. Repeat with remaining cake balls, melted candy and cones. When all are set, spoon remaining melted candy onto each cake ball, covering completely. Top each with 1 pecan half and remaining chopped pecans. Let stand until set.