Heat a large pot with 1 T butter and oil, over medium heat. Add the onion and black garlic to the pot. Cook until the onions have softened. Add the farro and the rosemary. Toast for 1-2 minutes. Reduce the heat to medium low and begin adding the water one cup at a time. Let the liquid absorb before adding the next cup. Stir the farro frequently. Reduce the liquid until the farro has a creamy consistency. Turn off the heat and add the salt, pepper, spinach, balsamic, and 2 T butter. Spoon onto 3 plates. Garnish with tomatoes, black garlic, and rosemary.