Preheat the oven to 300 degrees F.
Season meat with salt and pepper. In a heavy skillet or casserole, over high heat, sear the meat in 2 tablespoons extra-virgin olive oil, browning on all sides. Remove meat from the pan and set aside.
Lower heat to medium and gently sweat the sliced onion, celery, bay leaves, garlic, marjoram, and chile pepper in 2 tablespoons of the oil until soft and starting to turn golden. Add the tomatoes and tomato sauce to the pan, season, and let reduce for 5 minutes. Deglaze with wine, add in the lamb pieces, raise the heat to medium, and when the liquid comes to a simmer, cover and cook in the oven for 1 hour.
After 1 hour, add the greens to the pot, setting them directly on top of the meat and its juices. Cover and return to the oven for 30 to 45 minutes. Remove from the oven, discard the celery, bay leaves, and chile pepper, and transfer the meat and greens to a serving platter. Top with slivered cheese and serve immediately.
In a 3-quart saucepan, heat the olive oil over medium heat. Add the onion and garlic, and cook until soft and light golden brown, about 8 to 10 minutes. Add the thyme and carrot, and cook 5 minutes more, until the carrot is quite soft. Add the tomatoes and juice and bring to a boil, stirring often. Lower the heat and simmer for 30 minutes until as thick as hot cereal. Season with salt and serve. This sauce holds 1 week in the refrigerator or up to 6 months in the freezer.