In a large saute pan or cast iron skillet, heat the olive oil and saute the onion and pancetta over medium-high heat until the onion starts to soften and the pancetta gets a little crispy. Stir in the garlic and saute for another 30 seconds. Add the kale stems and cook until they begin to soften. Then add the chopped kale leaves and continue to saute, turning so the top layers rotate to the bottom of the pan and all the leaves start to wilt. Dinosaur or Lacinato kale have tender leaves and do not require a long cooking time. I like to remove the pan from the heat while the leaves are still bright green and before they are completely wilted. If desired, sprinkle a pinch of freshly grated nutmeg over the top.