Cauliflower, Pasta, and Cheese Gratin

8 c. water	1 c. (4 oz.) shredded sharp cheddar
6 c. cauliflower florets (1 ½ lbs.)	½ c. (2 ox.) grated fresh Parmesan cheese
3/4 tsp. salt, divided	¾ c. finely chopped green onions
8 oz. uncooked small seashell pasta	2 tsp. Dijon mustard
¼ c. all-purpose flour	¼ tsp. black pepper
3 c. low-fat milk	2 slices white bread
2 tsp. chopped fresh or ¾ tsp. dried thyme	2 tsp. butter, melted
3 garlic cloves, crushed

Preheat oven to 400 degrees.  Bring water to a boil in a large saucepan; add cauliflower and ½ tsp. salt to boiling water, and cook 4 min. or until tender.  Remove cauliflower with a slotted spoon, reserving cooking liquid; set cauliflower aside.  Bring cooking liquid to a rolling boil.  Add pasta, and cook 7 min. or until al dente; drain and set aside. 

Lightly spoon flour into a dry measuring cup, and level with a knife.  Combine flour and milk in a saucepan, stirring well with a whisk.  Stir in thyme and garlic and cook over medium heat until thick (about 8 min.), stirring constantly.  Remove from feat; stir in ¼ tsp. salt, cheeses, onions, mustard, and pepper.  Combine until coarse crumbs from to measure 1 cup.  Combine bread crumbs with butter; sprinkle evenly over cauliflower mixture.  Bake at 400F for 20 min. or until lightly browned.  Yield:  6 servings.