Cook carrots in boiling salted water to cover for 8 to 10 minutes or until tender
Drain and set aside
Melt 2 tablespoons butter in a heavy saucepan over low heat
Add celery and onion cook stirring often until tender
Add flour and next 3 ingredients stirring until blended
Cook 1 minute stirring constantly
Gradually add milk cook over medium heat stirring constantly until mixture is thickened and bubbly
Stir in cheese and carrots spoon into a lightly greased 1 12-quart casserole Combine breadcrumbs and remaining ingredients sprinkle over carrot mixture