- Cook spaghetti according to package directions, omitting salt; drain.
- Meanwhile, melt 1/4 cup butter in large saucepan over medium heat. Blend in flour; cook and stir 1 minute. Gradually stir in chicken broth until smooth. Cook, stirring constantly until mixture boils and thickens slightly. Stir in soymilk, ham, celery, onion, mustard and salt.
- Add spaghetti, stirring until evenly coated with sauce. Pour mixture into buttered 2-quart casserole or 13 x 9-inch baking dish.
- Bake in 350ºF. oven 15 minutes.
- Meanwhile, melt remaining 2 Tbsp. butter in small saucepan over medium heat; add bread crumbs. Cook and stir 2 minutes, or until lightly browned.
- Sprinkle bread crumbs evenly over spaghetti mixture. Return to oven and bake 5 minutes longer, or until bubbly.