For the chicken:
Butcher, or bone, the chickens so you have 4 halves with only the wing bones remaining. Marinate the chicken overnight in the wine, oil, rosemary, and garlic.
For the garnish:
Dice the pancetta and render it almost fully, put aside. Roast the whole garlic cloves until they are soft (foil works well) and put aside. Gather rosemary and put aside.
For the sauce:
In a large saute pan, brown onions and garlic in olive oil. Add chicken stock and rosemary and reduce ingredients over heat by half. Remove rosemary stems, and puree sauce until smooth and put aside.
In 2 large very hot oven proof saute pans place 2 chickens halves in each, with some olive oil. Place them skin side down, shake to ensure there's no sticking. Place on floor of a very hot oven, and roast until skin is crisp, and chicken is fully cooked.
Place several spoonfuls of sauce on plate, then your favorite type of potato next the chicken. Add the pancetta, roasted garlic cloves, and fresh rosemary garnish.