Prep Time: 10 minutes
Cook Time: 30 minutes
Preheat oven to 350°F. Prepare macaroni according to package directions.
Meanwhile, melt butter in large saucepan over medium heat. Stir in flour until smooth; cook and stir 2 minutes. Gradually add milk, stirring constantly, until mixture is slightly thickened.
Add cheese and onion. Cook, stirring constantly, until cheese melts. Add broccoli and macaroni; stir well.
Place in 3-quart casserole. Sprinkle English muffin pieces evenly over top. Bake 15 to 20 minutes or until muffin pieces are golden brown.