Warm Lentil Soup with Pancetta

3 ounces thinly sliced pancetta, cut into thin strips
1 1/2 cups coarsely chopped celery (about 3 stalks)
1 1/2 cups chopped white onion (about 1 medium)
3/4 cup chopped carrot
2 slices thick-cut bacon, chopped
1 head of garlic, most of outer skin removed, cut in half crosswise
2 small bay leaves
1 tablespoon chopped fresh thyme
1 pound French green lentils, rinsed, drained
10 cups (or more) low-salt chicken broth
2 tablespoons whipping cream
1 tablespoon white wine vinegar
8 green onions, cut crosswise into quarters then cut lengthwise into thin strips

Saute pancetta in heavy large pot over medium-high heat until crisp and brown. Using slotted spoon, transfer to paper towels to drain (do not clean pot). Spoon 1 tablespoon drippings into medium skillet and reserve.

Add celery, onion, carrot, bacon, garlic, bay leaves, and thyme to remaining drippings in pot and saute until vegetables are soft, about 8 minutes.

Add lentils and stir 1 minute.

Add 10 cups broth; bring to simmer. Reduce heat to medium-low and simmer uncovered until lentils are soft, about 1 hour.

Discard bay leaves and garlic. Using slotted spoon, transfer 2 cups lentils to small bowl; cover and reserve.

Working in batches, puree remaining soup until almost smooth. Return to pot.

Add cream and vinegar. Thin with more broth to desired consistency. Season with salt and pepper.

Reheat pancetta drippings in reserved skillet over medium-high heat. Add green onions; saute until wilted, about 1 minute.

Divide soup among bowls. Spoon lentils in center of each bowl, dividing equally. Garnsih with pancetta and green onions and serve.