Preheat oven to 400°F. Butter 13x9x2-inch glass baking dish. Steam carrots until almost tender, about 20 minutes. Transfer carrots to prepared dish. Melt butter in heavy medium skillet over medium-high heat. Add onion and celery and sauté until beginning to soften, about 5 minutes. Mix vegetables into carrots. Combine cheese and flour in medium bowl. Toss to coat cheese evenly with flour; mix in cream. Stir cheese mixture into carrot mixture. Sprinkle stuffing mix over. Bake carrots uncovered until sauce is bubbling thickly and topping is crusty, about 20 minutes.
