Zesty Chicken and Broccoli Casserole

This was on the menu for last week but unfortunately I got sick! Thankfully all is well now and I was able to make this tonight. This is a great recipe. I'm also happy it included borccoli! Chad won't eat it usually but mixed in with something he is more likely to like it :)
Give it a try!

Zesty Chicken and Broccoli Casserole
Source: A Taste of Home Cooking

3-4 broccoli crowns, cut into bite-size pieces
3/4 cup chopped onion (about 1/2 medium)
2 tablespoons oil
3 chicken breasts, cut into bite-size pieces
4 tablespoons butter, divided
1 1/2 cups milk
2 1/2 tablespoons flour
1/2 teaspoon salt
1/4 teaspoon pepper
Pinch of nutmeg
1 cup shredded sharp cheddar cheese
1/2 cup cream cheese, softened
1 cup mayonnaise (or sour cream)
1 (8-ounce) can sliced water chestnuts, drained
3/4 cup panko (Japanese breadcrumbs)

Preheat oven to 375°.

Cook broccoli and onion in a pan with 1 tablespoon oil until broccoli is just tender. Arrange in an even layer in an 11 x 7-inch baking dish coated with butter; set aside. Add second tablespoon oil to pan and cook chicken until golden-brown. Arrange on top of broccoli mixture.

Melt two tablespoons butter in empty pan over medium-high heat then add flour. Cook for 1 minute, then add milk, salt, pepper and nutmeg; bring to a boil. Cook 1 minute or until thick, whisking constantly. Remove from heat. Add cheddar and cream cheeses; stir until smooth. Stir in mayonnaise and water chestnuts. Spoon cheese mixture evenly over broccoli.

Place panko in a small bowl. Drizzle with remaining two tablespoons melted butter, and toss. Sprinkle breadcrumb mixture evenly over broccoli mixture. Bake for 25 minutes or until mixture begins to bubble and breadcrumbs brown.