I admit, I took the easy way out and adapted this amazing recipe from "Bowl of Delicious." What I loved is that it was EASY and needed very minimal ingredients, most of which were on hand. Talk about a crowd pleaser! Visit http://www.bowlofdelicious.com for some other amazing recipes.
Preheat oven to 475 degrees. Melt 4 tbsp. butter in small bowl; add 3 cloves minced garlic, 3 sprigs chopped rosemary, the zest of the two lemons, and plenty of Kosher salt and black pepper to taste. Set aside.
Place the onions in bottom of a cast iron Dutch oven. Reserve the end scraps. While fingerling potatoes are optional, if using, add them on top of the onions (about 1 1/2 lbs.).
Prepare chicken by removing giblets from cavity and patting dry with paper towels. Liberally season the cavity with salt and pepper.
Cut the zested lemons in half; reserve juice and save rinds. By now, the butter mixture will have hardened slightly. Using your hands, slather the mixture over every part of the chicken and under the breast skin. Stuff the cavity of the chicken with the lemon rinds, onion scraps, remaining 2 garlic cloves, and rosemary sprig/stems. Place in Dutch oven on top of sliced onions and potatoes (if using).
Pour reserved lemon juice over the chicken. Roast chicken, uncovered, for 15 minutes at 475, then reduce heat to 350 and cook for approximately 20 minutes per pound, or until internal temperature reaches 165 degrees. Allow the chicken to rest for at least 10 minutes before carving.