Celeriac (Celery Root) & Apple Soup

Directions

1. 1
   Melt butter in heavy large pot over medium heat.
2. 2
   Add celery root, apples, and onion. Cook until apples and some of celery root are translucent (do not brown), stirring often, about 15 minutes.
3. 3
   Add 4 cups broth. Cover and bring to simmer. Reduce heat to medium-low; simmer covered until celery root and apples are soft, stirring occasionally, about 25 minutes. Remove from heat; cool slightly.
4. 4
   Working in batches, puree soup in blender until smooth, adding more broth by 1/4 cupfuls to thin to desired consistency. Return soup to pot.
5. 5
   Season to taste with salt and pepper. DO AHEAD: Can be made 1 day ahead. Refrigerate uncovered until cold, then cover and keep refrigerated.
6. 6
   Puree chives, grapeseed oil, and pinch of salt in blender until smooth.
7. 7
   Preheat oven to 375°F
8. 8
   Arrange pancetta slices in single layer on rimmed baking sheet. Roast until pancetta is browned and crispy, about 18 minutes. Transfer to paper towels to drain. Crumble pancetta.
9. 9
   DO AHEAD: Chive oil and pancetta can be made 2 hours ahead. Let stand at room temperature.
10. 10
    Rewarm soup over medium heat. Divide soup among bowls. Sprinkle pancetta crumbles over each serving. Drizzle each bowl with chive oil.