Minestrone With Parmigiano-Reggiano

3 tablespoons extra-virgin olive oil

1 large red onion, chopped

2 large stalks celery, chopped

4 cloves garlic, chopped

2 large carrots, diced

1/4 pound thinly sliced pancetta, cut into thin strips

1/2 head Savoy cabbage, finely sliced, blanched and drained

1/2 bunch Swiss chard, finely sliced

1 large waxy potato, cut into 1/2-inch cubes

4 cups low-sodium chicken stock

3 medium tomatoes, seeded and diced

1 bouquet garni (1 sprig rosemary, 4 sprigs thyme, 1 bay leaf and 1 bunch parsley, tied together with kitchen twine)

3 cups cannellini beans (canned or cooked dried beans)

1 cup spinach, coarsely chopped

Kosher salt and freshly ground pepper

Grated Parmigiano-Reggiano cheese, for topping