Stir all of the chicken marinade ingredients together into a large bowl with a fitted lid. Submerge the chicken thighs and legs into the marinade. Cover and refrigerate for at least 2 hours, but up to overnight.
Drain chicken pieces, and discard marinade.
Preheat oven to 300 degrees F.
Line the bottom of a roasting pan with aluminum foil, then grease the top of the pan.
Arrange the chicken pieces over the top, greased roasting pan top.
Bake for 30 minutes.
Remove from oven, and set aside.
While the chicken is baking, brown the Cajun trinity of onion, green bell pepper and celery in a cast iron skillet. (Use the butter or oil to grease the skillet.)
When the trinity is browned, add the garlic. Cook for 1 additional minute.
When the roasting pan cools down some, use pot holders to take off the top. Remove and discard the water/pan juices and aluminum foil.
Wash the bottom of the roasting pan. Use more butter or oil to grease the bottom.
Arrange the potatoes along the bottom of the washed roasting pan bottom.
Sprinkle the garlic powder, paprika, onion powder and parsley flakes over the potatoes. Then, season to taste with salt, black pepper, and cayenne pepper.
Toss to combine well. Use a large spoon or even your hands to make sure that all of the potato slices are coated with seasoning.
Place all of the rosemary lemon sauce ingredients together in a microwave safe bowl.
Cover the bowl. Microwave for 30 to 45 seconds at full power, or until the butter melts.
Remove bowl from microwave. Stir to combine.
Arrange the pre-baked chicken pieces over the seasoned potato slices.
Baste the chicken pieces liberally with the sauce. Then, pour the remaining sauce atop all of the chicken and potato slices.
Bake for an additional 1 to 1 1/2 hours, or until the potatoes are very tender.
Use a digital meat thermometer to ensure that each chicken piece reads 165 degrees F before serving.
You can also use a whole, cut-up chicken to make this recipe.