Melt butter in a large skillet over medium heat add zucchini carrots and onion and saut 8 to 10 minutes or until tender Remove from heat stir in sour cream and next 3 ingredients Spoon into lightly greased 1-quart baking dish Sprinkle with breadcrumbs Bake at 350 for 20 minutes or until thoroughly heated Yield 4 servings