5 tablespoons unsalted butter

2 cup chopped leeks, white and light green parts only (about 3 medium leeks)

1 cup coarsely chopped celery

2 pounds (about 4 medium) red or Yukon Gold potatoes, peeled and cut into 1/2-inch cubes

6 cups chicken stock

1/2 teaspoon crushed dried rosemary or 1 1/2 teaspoons chopped fresh rosemary

10 ounces crumbled Stilton or other blue cheese

1/2 cup half-and-half

Kosher salt

2 Bartlett pears, ripe but not too soft

2 tablespoons unsalted butter

1/2 teaspoon sugar

1/4 teaspoon crushed dried rosemary or 3/4 teaspoons chopped fresh rosemary

Fresh rosemary sprigs, to garnish

To make the soup, in a large, heavy pot over medium heat, melt the butter. Add the leeks and celery, then saute until softened, about 5 minutes. Add the potatoes, stock and rosemary. Bring to a simmer, reduce heat and cook, uncovered, until the vegetables are very tender, about 20 to 25 minutes.

Transfer the soup to a blender or food processor, in batches if necessary, and puree. Return the soup to the pot and set over low heat. Whisk in the cheese until it melts, then whisk in the half-and-half. Heat for another minute, then season with salt.

Make the pears during the soup’s 20 to 25 minutes of simmering. To do so, peel the pears, halve them lengthwise, then core them. Cut each half into 1/2-inch-thick slices.

In a medium skillet over medium heat, melt the butter. Add the pear slices and cook until golden brown on the underside, about 3 to 4 minutes. Sprinkle the pears with the sugar, then turn and cook until golden brown on the other side, another 2 to 3 minutes. Sprinkle the pears with the rosemary.

To serve, ladle the soup into bowls and garnish with 2 to 3 pear slices and a rosemary sprig. Serves 6.