Preheat oven to 350 degrees and spray a 1 quart baking dish with cooking spray.

In a medium sauce pan, add about 1 in of water and the broccoli and bring to a boil.

Reduce the heat to a simmer, cover pan and cook for about 3 to 5 minutes or until the broccoli is tender and crisp. Drain broccoli.

While that is cooking, in a separate small sauce pan, mix the cornstarch, salt, a dash of pepper and milk until smooth.

Bring mixture to a boil and stir constantly for about 1 minute or until sauce is thickened.

Stir in the chopped onion and cheddar cheese until the cheese. Continue to stir until cheese is melted.

Add the cooked and drained broccoli to the cheese sauce and stir.

Pour mixture into baking dish, sprinkle with Parmesan cheese and bake for 25 to 30 minutes or until vegetables are tender.