Bring a large pot of salted water to a boil. Add the rice and cook until tender, about 15 minutes. Strain the rice and transfer to a large bowl, then bring a fresh pot of water to a boil. Drop the chard into the boiling water and cook until tender, about 7 minutes. Drain and rinse with cold water to stop the cooking, then squeeze dry and chop. Mix the chard and pancetta into the rice.
Chop the garlic, rosemary, red pepper flakes and 1/2 teaspoon salt into a fine paste using a knife or a mini chopper. Add to the chard-rice mixture along with the cheese, scallions, basil, parsley, lemon zest, nutmeg and 1/4 teaspoon pepper. Add the eggs and stir to combine.
Preheat the oven to 400 degrees. Remove the skin from the turkey breast in one piece and reserve. Place the meat smooth-side down on a cutting board and butterfly it: Slice down the middle of the breast with a sharp knife, but do not cut all the way through. Open the turkey like a book.
Sprinkle the meat with a teaspoon of cold water and cover with plastic wrap. Using the flat side of a mallet, or a rolling pin, pound the meat into a 1/2-inch-thick rectangle. Season with salt and pepper, then pile the chard stuffing down the center of the rectangle, packing it into a tight log. Fold the meat over the filling, overlapping the sides slightly. Stretch the turkey skin over the roulade to cover the seam and tie the roll at 2-inch intervals with kitchen twine. Fold in the ends and tie the roll lengthwise to seal.
Place the meat skin-side up on a rack in a shallow baking dish. Brush with the olive oil and season with salt and pepper. Pour the wine and 2 cups water into the dish and roast until a thermometer inserted into the roll registers 160 and the skin is golden and crisp, 50 minutes to 1 hour.
Transfer to a cutting board and let rest 15 minutes. Meanwhile, strain the pan juices. Remove the twine and slice the roll into 3/4-inch-thick pieces. Serve with the pan juices.