Chicken& Stuffing Pie

• 8 pkg herbed stuffing mix
• 4 colby (sliced)
• 2 pimento (diced)
• 1 american cheese
• 425 gr chicken (cooked)
• 170 gr chicken gravy
• 110 gr butter
• 180 ml chicken broth
• 100 gr thinly celery (sliced)
• 60 gr onion (chopped)