Cauliflower Soup with Toasted Hazelnuts and Gruyère

2 tbsp olive oil
1 cup chopped leeks
1/2 cup finely diced carrots
1/2 cup chopped celery
One 3 lb head of cauliflower, cut to yield 6 cups of florets (or packaged cauliflower florets)
4 cups chicken broth, plus up to 1 cup or more if needed
Kosher salt
1/8 tsp cayenne pepper
Freshly ground black pepper
1/2 cup whole milk, plus up to 1/2 cup more if needed
1/3 cup grated Gruyère
1/4 cup coarsely chopped toasted hazelnuts (see cooking tip)
1 tbsp chopped chives or flat leaf parsley, for garnish

1.In a large, heavy pot (with a lid) over medium heat, heat the oil until hot. Add the leeks, carrots, and celery and sauté, stirring, until just slightly softened, about 5 minutes. Add the cauliflower florets and stir and cook 2 minutes more.

2.Add 4 cups of broth, 1/2 teaspoon salt, cayenne pepper, and several grinds of black pepper. Bring the mixture to a simmer, then reduce the heat to medium low. Cover and cook the soup at a gentle simmer until the vegetables are tender when pierced with a small sharp knife, 20 to 25 minutes or more.

3,Purée the soup in a food processor, blender or food mill, and return the soup to the pot. (Or use an immersion blender to purée the soup in the pot.) Whisk in 1/2 cup milk. If the soup is too thick, add up to 1 cup or more broth and 1/2 cup additional milk. Season the soup with additional salt if needed. (Soup can be prepared one day ahead; cook to this stage, then cool, cover, and refrigerate. Reheat over medium heat, stirring often.)

4.Ladle the soup into 4 individual bowls. Garnish each serving with a sprinkle of cheese, some toasted hazelnuts, and chives or parsley.

Serves 4

Cooking tip: To toast hazelnuts, spread on a rimmed baking sheet and place in a preheated 350- degree F oven until lightly browned and fragrant, about 8 minutes. Watch carefully. Remove and place nuts in a kitchen towel and rub off as much of the skins as possible.

Adapted from Soup Nights by Betty Rosbottom (Rizzoli 2016)