I made this tonight. It is from Sundays at Moosewood Restaurant . I did not puree the soup but rather let it cook until it was quite thick and smooth. I also did not use the cream (for the obvious reasons). I have also made it without the parsnips. This is an excellent soup!
Hernerakkaa (Yellow Split Pea Soup)
Serves 6 Generously
2 cups dried yellow split peas
8 cups water or vegetable stock
2 medium potatoes (I use 2 cups frozen hash browns)
2 large carrots (I use 1 cup of the pre-cut matchstick carrots)
3 celery stalks
1 large onion
1 turnip, peeled
2 parsnips, peeled
2-3 tsp. dry mustard (or 2-3 Tbsp. prepared mustard) (or to taste)
dash of allspice
1 tsp. ground cumin seeds
1 tsp. dried marjoram
1 tsp. dried thyme
2 tsp. salt (or to taste)
plenty of freshly ground black pepper
1 cup heavy cream (optional)
dark bread croutons or cubes of toast (optional)
Rinse the split peas. In a large soup pot, bring the split peas and the water or stock to a boil. Coarsely chop the vegetables and add them to the water as it comes to a boil. Lower the heat and simmer for about 1-1/2 hours or until the peas are very soft and almost disintegrating. use a heat diffuser, if needed, to prevent scorching.
Puree the soup in batches in a blender or food processor, until it is quite smooth and an even yellowish color. The pureed soup will be very thick. Add the spices and herbs and season with salt and pepper to taste. Reheat gently.
If you are using heavy cream, whip it until stiff. Serve the soup steaming hot, garnished with croutons or cubes of toast and dollops of whipped cream.
While I don't mind the color of regular split pea I know it really turns some people off.
Even with the milk added, it is extremely thick. A good stick to your ribs soup for the middle of winter! 
