Carrot and leek soup with herbed croutons

 Carrot and leek soup with herbed croutons 

ServeS  6
 3  oz. (6 tbs.) unsalted butter
 1  medium yellow onion, chopped
 2  small leeks (light-green and white parts only), sliced
 2  large cloves garlic, chopped Kosher salt and freshly ground black pepper
 3  cups lower-salt chicken broth
 2  lb. carrots, sliced 1/4 inch thick 
 3  fresh or 2 dried bay leaves
 2  sprigs fresh thyme
 4  oz. crusty bread, cut into
1/2   -inch cubes (2 cups)
 11/2    tbs. chopped fresh chervil
 1  cup plain full-fat or low-fat yogurt

Adding yogurt to the soup makes it smooth and creamy. If you can’t find chervil (a relative of the carrot), use dill instead.

1. position a rack in the center of the oven and heat the oven to 350°F. 
2. In a 4- to 5-quart saucepan, melt 3 Tbs. of the butter over medium heat. 
Add the onion, leeks, garlic, 1/2   tsp. salt, and 1/4   tsp. pepper; cook until softened 
and light golden-brown, about 10 minutes.
3. Add the broth, carrots, bay leaves, thyme sprigs, and 1/2   cup water; bring to a 
boil over medium-high heat. reduce the heat to medium and simmer until the 
carrots are tender, about 15 minutes. 
4. Meanwhile, melt the remaining 3 Tbs. butter in a 3-quart saucepan over
medium heat. Add the bread cubes and chopped chervil and toss to coat 
evenly. spread on a rimmed baking sheet, season with salt, and bake until 
golden, 8 to 10 minutes.
5. when the vegetables are tender, discard the bay leaves and thyme sprigs. 
with a regular or a hand blender, purée the soup (work in batches if using a 
regular blender). stir in the yogurt. If you prefer a thinner texture, add a little 
water. season to taste with salt and pepper, and serve garnished with the 
chervil croutons.