Wash the kale leaf by leaf to remove any dirt or sand. Remove and discard the thick stems. Chop the leaves and thin stems coarsely and set aside. Heat the olive oil in a large sauté pan over medium heat. Add the onion and kale and cook, stirring occasionally, for 2-3 minutes. Add the garlic and cook briefly. Stir in the farro, currants, parsley and salt and pepper. Pour in the stock. Bring the liquid to a boil. Boil for one minute. Turn the heat to medium-low, cover the pan and cook for about 25 minutes or until all the liquid has been absorbed. Sprinkle with the pignoli nuts. Spoon into a serving bowl and sprinkle with Parmesan cheese.