Gather all ingredients, as well as your dutch oven (or cast iron skillet), and preheat the oven to 425 degrees
Chop all potatoes in 4 inch chunks. Peel several garlic cloves (5-10 or to your liking). Place the chopped potatoes at the bottom of the dutch oven along with the peeled cloves of garlic as well as 3-4 sprigs of rosemary (see picture above)
Season the potatoes in the dutch oven with salt and pepper
Slice the lemon in half, slice the remaining garlic head in half, and have several more sprigs of rosemary on hand
Remove your whole chicken from the package and discard the giblets (all the stuff in the inside)
Where the giblets were removed from is where you will place the ingredients to flavor the chicken. Add one lemon half first, then half a garlic head, then the rosemary, next the other half of the garlic head and finish with the last lemon half. There really is not a method to this, but I've found this typically works to fit everything.
After the chicken is stuffed, take the butter and spread it all over the chicken until its evenly coated. Finish by seasoning generously with salt and pepper.
Next, place the stuffed chicken on top of the potatoes and other ingredients in the dutch oven or skillet
Place the dutch oven or skillet in the oven without a lid or covering and cook for 75 minutes. I usually end up cooking mine for 90 minutes but check it at 75 minutes. The internal temperature should be 165 and the juices should run clear