In a large soup pot, melt butter over medium heat.
Saute onions and garlic until golden.
Add parsnips and celery root and saute about 5 minutes more.
Add white wine, stock, water and beans and bring to a boil.
Reduce to a simmer and cook until veggies and beans are very soft.
Turn off heat and puree soup carefully in small batches.
Return soup to pot, add in cream and season with salt and white pepper to taste.
Garnish and serve!
Notes
The time it takes for the soup to cook depends mostly on the dried beans. Smaller beans cook faster, so I'm a big fan of Bob's Red Mill Small White Beans. However if you are short on time, use canned white beans and rinse them very well.