COMBINE PASTA AND BROTH in a small pot, cover, place over medium-high heat, bring to a boil and cook 5 minutes, or until barely soft. Remove from heat and transfer contents of the pot to a work bowl. Add salt and pepper. Meanwhile, heat the olive oil over medium heat in a medium skillet on the stove, add the onions, garlic and anchovies and cook, stirring occasionally, until onions are softened, about 8 to 10 minutes. Scrape the mixture into a food processor, add basil and puree until coarsely ground. Add onion mixture to the pasta in the mixing bowl and add egg white and bread crumbs. Mix well. Chill in the refrigerator. Pull the tenderloins off the meat side of each breast and set aside. Remove the skin in 1 piece and set aside. Place breasts between layers of plastic wrap or wax paper and flatten to a 3/8-inch thickness. Gently flatten the tenderloins. Lay the breasts down on what was their skin side and place about 1/3 cup stuffing on each breast, leaving a 1-inch border. Gather up the edges around the stuffing as best you can. Lay a tenderloin on the opening and wrap each bundle with the skin. Preheat oven to 350F. Place the bundles in a baking dish just large enough to hold them comfortably. Pour in Marsala and vinegar, cover and place in oven for 20 minutes. Arrange the chicken on a platter and pour the cooking juices into a saucepan. Place saucepan over high heat and boil until reduced by half. Remove from the heat, pour the sauce into a mixing bowl and vigorously whisk in 3 tablespoons olive oil. Pour the sauce over the chicken and serve immediately.