Snap off and discard tough ends of asparagus and cut into 1 inch slanting slices.
In a 1 1/2 quart casserole, place asparagus and water.
Cover with a lid or plastic wrap.
Microwave on HIGH (100%) for 6 to 7 minutes (stirring after 4 minutes) or until tender crisp.
Let stand, covered, for 1 minute.
With a slotted spoon, transfer asparagus to a paper towel, reserving juices; set asparagus aside.
Add butter to the reserved juices.
Microwave, uncovered, on HIGH (100%) for 30 seconds.
Stir in green pepper and onion.
Microwave, uncovered, on HIGH (100%) for 4 minutes, stirring after 2 minutes.
Sprinkle with flour, salt, and pepper; mix until blended.
Microwave, uncovered, on HIGH (100%) for 1 minute or until bubbly.
With a wire whip, beat in milk.
Microwave, uncovered, on HIGH (100%) for 2 minutes (stirring after 1 minute) or until bubbly.
Stir in cheese, mixing until it is melted; then gently stir in asparagus.
Sprinkle with croutons.
Microwave, uncovered, on HIGH (100%) for 3 minutes, rotating dish 1/4 turn after 2 minutes.