In a small sauce pan, whisk 1 cup milk with the gluten-free flour and heat over medium.
Add the butter, bullion and salt.
When it starts to bubble, reduce heat and heat for a couple minutes, stirring often. Set aside.
Cook broccoli according to package and chop up.
Put the broccoli into an 8 inch square dish
Top with chicken
In a bowl mix together the milk, sour cream, and cream of chicken soup mixture.
Pour over the chicken
Top with cheese
Mix together the melted butter and bread crumbs and sprinkle on top of cheese.
Season with salt and pepper
Cook at 450 degrees for 15-20 minutes.