Remove 24 pepperoncini from jar; remove and discard stems and seeds. Drain peppers on paper towels. Stuff each with a piece of chicken and a cheese strip (cheese may need to be cut to fit in some peppers).
Place one sheet of phyllo dough on a work surface (keep remaining dough covered with waxed paper to avoid drying out). Spritz dough with butter-flavored spray. Repeat three times; stack sprayed phyllo dough. Cut stacks into four pieces, about 6-1/2 in. x 4-1/4 in. each.
Center one stuffed pepper on one long side of each phyllo stack; roll up and twist the ends to seal. Repeat with remaining peppers and dough. Place on ungreased baking sheets. Drizzle butter over center of firecrackers. Bake at 375° for 18-22 minutes or until golden brown. Tie ends with chives if desired.
Look for pepperoncini (pickled peppers) in the pickle and olive section of your grocery store.