See blog post for more details and suggestions.
For a vegetarian version:
Feel free to omit the pancetta. Use olive oil to cook the onion.
Use vegetable broth instead of chicken broth.
Use any medium-ish can or jar of white beans, like cannellini or navy etc. The size isn't crucial, unless of course we are talking about the industrial sized cans! You can always adjust the broth to thin it out if you desire.
Feel free to use half and half, or your favourite nut milk instead of cream.
You can use your favourite greens, just chop them finer if they are heartier greens like swiss chard or collard greens.