Simmer carrots, garlic, broth, and salt in a 1- to 2-quart heavy saucepan, covered, until carrots are very tender, 12 to 14 minutes. Purée mixture with cream and butter in a food processor until smooth. Cooks note: Purée can be made 1 day ahead and cooled, uncovered, then chilled, covered. Reheat in an ovenproof dish, covered with foil, in a preheated 425°F oven 5 to 10 minutes. Makes 2 servings (about 2/3 cup)