How To make Gold Medal Corn Zucchini Casserole

1 1/2 tablespoons butter
1 cup onion

chopped
2 medium zucchini, trimmed, quartered lenghtwise :

thinly
sliced (about 1 lb.) 3 1/2 cups fresh corn kernels or frozen -- thawed
1/2 teaspoon salt
1/2 teaspoon pepper
3 1/2 tablespoons flour
1 1/2 cups 2% low-fat milk
Crumb Topping 2 tablespoons butter
2 teaspoons garlic

minced
3/4 cup bread crumbs
1 teaspoon oregano
6 ounces Monterey Jack or Italian Fontina :

cut into 1/2"
cubes
For casserole: Melt butter in a large skillet over medium heat. Add onion and cook, stirring often, until soft, but not browned, about 6 minutes. Add zucchini and cook 5 minutes until crisp tender. Stir in corn, salt and pepper. Cook about 3 minutes until hot, then stir in flour and cook 2 minutes more. Gradually stir in milk. Bring to a simmer, stirring often and cook 5 minutes until thickened and creamy. Let cool.
For topping: Melt butter in a large skillet. Add garlic and stir over low heat 1 minute without browning. Add bread crumbs and oregano; cook, stirring often, until crumbs are toasted. Let cool.
Stir cheese into corn mixture and spoon into a shallow 2-quart baking dish. Sprinkle with topping. Heat oven to 350. Bake casserole for 30 minutes or until hot and bubbly.