My Mother's Cauliflower Soup

1 medium head of cauliflower, cleaned and broken into bite-sized bits
2-3 carrots, peeled and sliced
1-2 ribs of celery, sliced
4-1/2 cups homemade chicken or vegetable stock
8 fresh crimini mushrooms, sliced
1 medium onion, chopped
1/4 cup butter
2 tablespoons flour
1/2 cup heavy cream

¼ cup chopped fresh parsley
Salt and Freshly ground black pepper, to taste

In a medium stockpot, bring cauliflower, carrots, and celery to a boil in stock. Meanwhile, in a 9-inch sauté pan, saute mushrooms and onion in butter until onions are translucent. Add flour, stirring constantly for 1-2 minutes.  Add one cup of the warm stock to the flour mixture, stirring until thick. Pour mushroom/onion mixture into the cauliflower/carrot/celery broth and stir to combine. Stir in cream, parsley, and pepper to taste. Heat through. Serves 6-8.