Instructions:

Preheat oven to 350 degrees F and prepare a casserole dish with cooking spray.
Take butter and melt it over medium heat in a medium saucepant. Add in garlic and cook until fragrant. Flour must be stirred well and cooked till slightly golden brown. Slowly whisk in milk and 1/2 cup broth. Remember leaving it on untill it reaches a light boil gentely then begin to thicken a bit. Stir in sour cream, chicken, vegetables and cheese. Add mixture to prepared casserole dish.
Mix bread cubes in a separate bowl. You are free to remain broth (better be 1/2 cup) and seasonings as desired or needed. One more thing, Remember to put it on top of casserole mixture.
If using raw chicken, leave the bake uncovered for almost 30-45 minutes until chicken is cooked through, as well as you can keep the bake undercovered until heated through in case you are using cooked chicken.

Quick Tip: Sprinkle some cheese on top.