Shells with Cauliflower and Ham

Heat oven to 400°F. Spray 13x9-inch (3-quart) glass baking dish with cooking spray.

In 3-quart saucepan, heat 8 cups (2 quarts) water to boiling. Add cauliflower and 1/2 teaspoon of the salt; cook 4 minutes or until tender. Remove cauliflower with slotted spoon to large bowl. Heat cooking liquid to boiling. Add pasta; cook 6 minutes. Drain; add pasta to cauliflower.

In 2-quart saucepan, stir flour and milk with whisk. Add garlic; cook over medium-high heat about 8 minutes, stirring frequently, until thickened. Remove from heat; stir in cheeses, mustard, pepper and remaining 1/4 teaspoon salt. Pour cheese sauce over cauliflower mixture. Stir in ham. Spoon mixture into baking dish.

Place bread in food processor. Cover; process until coarse crumbs form. In small bowl, mix bread crumbs and butter; sprinkle over casserole. Bake uncovered 20 minutes or until lightly browned.