Celery-Root Bisque

This is actually a hybrid recipe of this one and this one from the Boistfort site. This is my first experience cooking with celery root.

Ingredients:
2 tablespoons butter
1 tablespoon olive oil
2 large leeks (white and pale green parts only), thinly sliced (about 2 c.)
1 large onion, chopped
Celery root (celeriac), peeled and cut into 1/2-inch cubes (about 5 1/2 c.)
Russet potatoes, cut into 1-inch pieces (about 12 oz.)
2 c. chopped celery stalks (including leaves)
1 1/2 t. minced fresh thyme
1 bay leaf
7 c. chicken broth (or 7c. water and 7 t. chicken base, which is what I used)
1/3 c. whipping cream
Salt, to taste
Freshly ground black pepper, to taste
Additional chopped fresh thyme (as a garnish)

Melt the butter with the oil in a large stock pot over medium heat. When sizzling subsides, add the leeks and onion, and sauté for about 10 minutes, stirring occasionally. Stir in the celery-root cubes, potato cubes, chopped celery, 1 1/2 t. thyme, and the bay leaf. Add broth, increase heat to high, and bring to boil. Reduce heat, cover, and simmer until vegetables are tender, about 40 minutes. Compost bay leaf (oops--I forgot to do this and puréed it together with everything else). Using immersion blender, carefully purée soup in pot. (Alternately, carefully purée in batches in a regular blender or food processor.) Stir cream into soup. Season to taste with salt and pepper. Ladle soup into bowls. Garnish with additional chopped thyme.

Comments:
This is very, very good. It's smooth, rich (but not overly so), and has a beautiful celery flavor. The chopped thyme sprinkled on top complements the flavor of the bisque so well.

Happy birthday, Steve!