Melt 2 tablespoons butter in a large skillet over medium heat. Add onion and garlic and cook until softened, about 5 minutes. Stir in flour and cook about 1 minute more.
Whisk in chicken broth, cream, salt, pepper, and mustard. Bring to a simmer and cook for about 5 minutes, stirring occasionally, until sauce is thickened.
Remove from heat and stir in Parmesan cheese, lemon juice, and parsley. Add chicken and broccoli and stir to combine.
Transfer mixture to a 2-quart baking dish. Sprinkle with Cheddar cheese. In a small bowl, combine cracker crumbs and melted butter. Sprinkle over the top of the casserole.
Bake for 25 minutes, or until cheese is melted and bubbly. Allow to cool for 10 minutes before serving.
Interesting Facts
Chicken Divan was first created in the 1950s at the Divan Parisienne restaurant in New York.
It is a classic comfort food and an excellent way to use up leftover cooked chicken.
It can be served as a main dish or a side dish.
It is a great way to get your family to eat more vegetables.