Cook the spinach in a large frying pan in a little olive oil over a very high heat until just wilted. Add the garlic and allow to cool. Squeeze out when cool, then season. Stuff the turkey legs with the spinach, and re-form into approximately their previous shape. Tie about four times.
Heat a roasting dish with a little oil and add the pancetta and the turkey bones. Cook over a medium flame until the pancetta starts to colour. Add the turkey legs and soffritto, and continue sweating for 10 minutes or so over a medium flame. At this point add the red wine and broth. Place in the roasting dish in the preheated oven and roast for an hour, turning and basting the turkey often. This is left uncovered and the sauce will reduce to a glaze. Add more water if needed.
If after an hour the turkey is done but the sauce is still thin, remove the turkey and turn the heat up and reduce on top of the stove until strongly flavoured and syrupy. Pick out and discard the bones and skim the fat off the sauce. Slice the turkey rolls across the grain and serve with the pancetta and soffritto sauce.