In a large sauté pan, melt butter with the olive oil over medium high heat. Sprinkle all sides of chicken pieces with salt and pepper. Add to pan, skin side down, and sauté until well browned, about 5-6 minutes per side. Remove chicken pieces to a plate and reserve.
Return pan and heat over medium flame. Add onions and sauté, tossing occasionally, until well browned, about 5-6 minutes.
Add Marsala wine, stock, and orange juice to pan, bring to a boil and reduce liquid by half. Add prunes, bay leaves, and orange peel to pan. Return chicken and any accumulated juices. Cover and reduce heat.
Cook chicken for about 30 minutes or until an instant read thermometer registers 170º F.
Remove bay and orange peel for service. Serve chicken pieces with pan juices, prunes and onions spooned over. May be served with brown rice tossed with toasted slivered almonds if desired.