Heat a large pot and render the bacon. Add the onion, leeks and parsnips and cook a few minutes until the onions are quite tender. Season the vegetables with some salt and stir in the thyme and bay leaves. Add the flour and stir for a minute or two. Add the broth and water, bring to a boil, lower heat and simmer until the parsnips are fork tender. Stir in the half & half, bring back to a boil and simmer for a couple minutes more.
Season with additional salt and pepper and serve.