chicken and broccoli casserole

i made this for the first time for my bible study group and they all loved it.

3 tablespoons unsalted butter
3 tablespoons all purpose flour
2 cups chicken broth
1 shallot, minced
1 teaspoon salt
1/2 teaspoon ground black pepper
1 tablespoon fresh lemon juice
1/2 cup sour cream
2 cups grated parmesan cheese
3 cups frozen broccoli florets, thawed
1 1/2 pounds boneless, skinless chicken breast, cooked and shredded
1 cup cracker crumbs (i used ritz crackers)

1. preheat oven to 325 degrees.
2. in a saucepan, melt the butter over low heat, and add the flour.cook for about 3 minutes.
3. add the broth and shallot, and increase the heat to bring the mixture to a boil.
4. reduce to a simmer, stirring occasionally until the mixture thickens, about 10 minutes.
5. add the salt, pepper, and lemon juice.
6. remove from heat, and stir in the sour cream and 1/4 cup of parmesan.
7. arrange the broccoli in a 2 quart casserole, and pour half the sauce over it.
8. arrange the chicken on top of the broccoli, and pour the remaining sauce.
9. top with cracker crumbs and remaining cheese.
10. bake for 20 minutes.
11. then put the dish under the broiler until the cracker crumbs are golden brown, about 1 minute. (don't do longer than that it will burn)