1. Pound butterflied breast halves to flatten, season with salt and pepper, and refrigerate overnight.
2. Preheat oven to 400°F.
3. In a 12- to 14-inch sauté pan, heat 3 Tbsp oil over medium-high until smoking. Add pancetta and cook until golden brown, 7 to 9 minutes. Add pork and cook for 25 minutes or until it starts to brown, stirring regularly.
4. Drain all but 4 Tbsp fat from pan and add chestnuts and prunes. Continue cooking for 8 minutes or until prunes start to soften. Remove from heat and allow to cool for about 20 minutes.
5. Add bread crumbs, Parmigiano, eggs, 2 Tbsp pepper, nutmeg, and herbs and mix well with your hands. (Overmixing can result in a lead torpedo for stuffing, so do not overdo it.) Place turkey breasts on a cutting board, skin side down, and divide stuffing between them. Roll each breast like a jelly roll and tie firmly in several places with butcher's twine. Place on a rack in a roasting pan, skin side up.
6. Pour 2 cups wine over turkey and season with salt and pepper. Roast until breasts are dark golden brown outside and a meat thermometer reads 165° at fattest part, about 1 hour (plus or minus 10 minutes).
7. Remove and allow to rest 15 minutes before carving. Add remaining 1 cup wine to roasting pan and deglaze, scraping with a wooden spoon. Cook for 5 minutes, then add remaining 1/4 cup oil. Shake pan to emulsify sauce and season with salt and pepper.
8. Carve roast into 1/2-inch-thick slices and drizzle with pan sauce. Serve.
Serves 8. Per Serving: 560 calories, 14g carbs, 53g protein, 32g fat, 175mg cholesterol, 310mg sodium, 2g fiber