Heat a large skillet over medium high heat. Coarsely chop the greens of clean red chard. Add oil, pancetta, and chopped onion to the pan and cook 2 or 3 minutes until onions begin to soften and pancetta is lightly browned. Add chopped chard to pan in large bunches, adding remaining chard as the greens wilt.
Sprinkle in raisins, pour in broth and season with salt and nutmeg. Bring liquid to a boil, reduce heat and simmer greens 10 to 15 minutes until greens are no longer bitter and you are ready to serve. Raisins will plump as the dish cooks through.