Cream of asparagus soup

2 large leeks
2 tablespoons butter
4 cups ready-to-serve chicken broth
2 medium potatoes, peeled and diced
1/2 teaspoon salt
1/4 teaspoon pepper
1 pound asparagus
1/2 cup whipping cream

Trim the roots and the leaves from leeks, leaving only the white and about 2 inches of the green sections. Rinse well; split lengthwise and slice crosswise about 1/4 inch thick. Sautй leeks in butter in Dutch oven over low heat about 10 minutes or until softened. Stir in chicken broth, potatoes, salt and pepper. Bring to a boil over high heat. Meanwhile, trim off tips (about 1 1/2 inches) from asparagus; reserve for garnish. Trim off woody stem ends; discard. Chop remaining asparagus into 1-inch pieces. Add to boiling soup. Reduce heat and simmer, uncovered, about 10 minutes or until vegetables are tender. Transfer soup to work bowl of food processor or blender; process until pureed. Return soup to clean saucepan. Stir in cream; heat through.