Heat some olive oil in a heavy soup pot, and add the finely chopped shallots, carrot, celery, garlic, and bacon. Mix the vegetables well, and season with salt and pepper. Sweat the vegetables until soft, adding a little water to help create steam. Make sure the vegetables do not crisp and burn by adding a little additional water, and stirring.
When the vegetables are soft, add the cabbage slices and the sage. Mix well. Add the stock, bring the soup to the boil and then lower the heat. Within five minutes the soup will be ready.
Pour the soup into warm serving bowls and then sprinkle fresh Parmiggiano reggiano shavings on top.