Preheat the oven to 350°F.

Lightly spray a 9×13-inch casserole dish with nonstick spray.

Fill a medium-sized saucepan with water. Heat the water on medium high heat, to a slow rolling boil.

Add the broccoli florets to the boiling water, and cook for 3 to 4 minutes.

Using a colander, drain the broccoli florets. Keep the florets in the strainer until it is time to add them to the sauce.

In a medium-sized stock pot, over medium heat, melt the 3 tablespoons of butter.

Add the finely diced onion and saute for 5 to 7 minutes, or until the onions are soft and translucent.

Whisk in the 3 tablespoons of all-purpose flour, garlic powder, onion powder, chicken soup base, paprika, salt and black pepper.

Whisking constantly, allow the flour and onion mixture to cook for 30 seconds to 1 minute.

Slowly whisk in the 2 cups of milk and 2 cans of cream of chicken soup. Keep whisking until the sauce is smooth and thickening.

Whisk in the sour cream and softened cream cheese, whisking until the sauce is smooth.

Remove from heat and add the 1½ cups of the shredded Colby jack cheese, whisking until smooth.

Add the 2½ cups of cooked rice and the completely drained broccoli florets to the sauce.

Stir well, and pour into the prepared casserole dish.

Bake for 25 minutes, uncovered.

Remove the baking dish from the oven, sprinkle the remaining 1 cup of shredded cheese and place back in the oven to cook for a further 10 minutes.

Let sit for 10 minutes to firm up. Serve hot.