Celery Root and Potato Puree with Roasted Jerusalem Artichoke "Croutons"

Ingredients

• 2 medium celery roots trimmed peeled cut into 1-inch cubes ( 8 cups) (celeriac;)
• 1  bay leaf fresh
• 1 teaspoon thyme leaves fresh chopped (for garnish)
• 3  garlic cloves peeled
• 8 ounces jerusalem artichokes scrubbed (also called sunchokes)
• 2 cups low-salt chicken broth 
• 0.5 tablespoon olive oil extra-virgin
• 1 pound russet potatoes peeled cut into 3/4-inch cubes ( 3 cups)
• 3  thyme sprigs fresh
• 4 tablespoons butter unsalted divided ()
• 2 cups milk whole

Equipment

• bowl
• oven
• pot
• potato masher
• microwave

Directions

1. Combine first 7 ingredients in heavy largepot.
2. Add enough water to cover.
3. Sprinklewith salt. Bring to boil, reduce heat tomedium, and simmer with lid slightly ajaruntil vegetables are tender, 15 to 20 minutes.
4. Drain; return to pot. Discard thyme sprigsand bay leaf. Stir over medium heat to dryvegetables. Using potato masher, mashvegetables until coarsely pureed. Mash in3 1/2 tablespoons butter. Season with salt andpepper. DO AHEAD: Can be made 1 day ahead.
5. Transfer to microwave-safe bowl; cover andchill. Rewarm in microwave before serving.
6. Preheat oven to 425°F.
7. Cut Jerusalemartichokes into 1/2-inch cubes.
8. Place in mediumbowl; add oil, sprinkle with salt and pepper,and toss to coat. Dot with remaining 1/2tablespoon butter.
9. Transfer to rimmed bakingsheet; roast until tender and golden brown,turning occasionally, about 25 minutes.
10. Place celery root and potato puree inserving bowl.
11. Sprinkle Jerusalem artichokesand chopped thyme over and serve.