Preheat your oven to 350°F (175°C).
Place the frozen chopped broccoli in a microwave-safe dish, add 2 tablespoons of water per 8 oz of broccoli, and cover. Microwave on HIGH for 8-10 minutes, stirring after the first 3-4 minutes. Season to taste.
After microwaving, carefully drain and squeeze out the excess water from the broccoli to ensure your casserole is not watery. Placing scoops of broccoli in the center of a 4-5 layer square of paper towel and squeezing works
In a large bowl, combine the microwaved broccoli, cream of chicken soup, flour, sour cream, grated carrots, grated onion, salt, and pepper. Mix well. Use salt/pepper till it tastes good
Transfer the mixture to a large baking dish. 2qt works
In a separate bowl, mix the herb seasoned stuffing with melted butter, then sprinkle it over the broccoli mixture.
Bake in the preheated oven for about 50mins, or until the casserole bubbles around the edges.
Let it sit for a few minutes before serving.