- 2 tablespoons (1/4 stick) butter
- 1 cup chopped onion
- 2 small celery stalks, stalks and leaves chopped separately
- 1 medium leek, sliced (white and pale green parts only)
- 1 large garlic clove, chopped
- 1 1/2 pounds red-skinned sweet potatoes (yams), peeled, cut into 1-inch pieces (about 5 cups)
- 4 cups chicken stock or canned low-salt chicken broth
- 1 cinnamon stick
- 1/4 teaspoon ground nutmeg
- 1-1/2 cups half-and-half or light cream
- 2 tablespoons pure maple syrup
- Melt butter in heavy large pot over medium-high heat. Add onion and sauté 5 minutes. Add chopped celery stalks and leek and sauté until onion is translucent, about 5 minutes. Add garlic and sauté 2 minutes.
- Add potatoes, chicken stock, cinnamon, and nutmeg; bring to boil. Reduce heat and simmer uncovered until potatoes are tender, about 20 minutes.
- Remove cinnamon stick and discard. Working in batches, puree soup in blender until smooth. Return to pot. Add half and half and maple syrup and stir over medium-low heat to heat through. Season soup to taste with salt and pepper. (Can be prepared 1 day ahead. Cool soup slightly. Cover and refrigerate soup and celery leaves separately. Bring soup to simmer before continuing.)
- Ladle into bowls. Sprinkle with celery leaves.