White Macaroni and Cheese

1/4 c. butter
1/4 c. flour
1/2 tsp. salt
1/2 tsp. ground mustard
1/4 tsp. pepper
2-2/3 c. milk
1-1/3 c. cheddar cheese
1-1/3 Monterey Jack cheese
1/2 tsp. Worcestershire sauce
3 c. cooked elbow macaroni

In a saucepan, melt butter. Stir in the flour, salt, mustard, and pepper until smooth; gradually add milk. Bring to a boil; cook and stir for 1 minute or until thickened. Reduce heat. Add the cheeses and Worcestershire sauce; stir until cheese is melted. Fold in macaroni. Pour into a 2-qt. baking dish coated with nonstick cooking spray. Bake, uncovered, at 350 degrees for 10-15 minutes or until bubbly.