Place the frozen broccoli cuts and diced frozen onions together in a large microwave safe bowl.
Microwave on high for 2 minutes then remove and stir.
Return to the microwave for another 2 minutes and stir again.
Continue microwaving in 2 minute intervals until the broccoli is fully thawed and tender when pierced with a fork. This usually takes 4 to 6 minutes total.
Remove the bowl from the microwave and let the broccoli cool for 2 minutes until it is cool enough to handle.
Use kitchen scissors to cut the broccoli pieces down into smaller chunks about the size of a dime. This ensures even distribution throughout the casserole and makes every bite the perfect size.
Prepare the Minute Rice according to package directions. For extra flavor cook the rice in chicken broth instead of water.
Preheat your oven to 350 degrees and spray a 9x13 baking dish with cooking spray and set aside.
In a very large mixing bowl add the cooked Minute Rice.
Add the entire jar of Cheez Whiz to the bowl.
Pour in the can of cream of mushroom soup.
Pour in the can of cream of chicken soup.
Add the cup of milk.
Stir everything together until fully combined and the Cheez Whiz is evenly distributed throughout with no streaks remaining.
Add the cooked broccoli and onions to the bowl.
Fold the broccoli and onions gently into the rice mixture until evenly distributed.
Season generously with salt and pepper and stir to combine.
Taste the mixture and adjust seasoning as needed before baking.
Pour the entire mixture into the prepared baking dish and spread it into an even layer using a spatula.
Place the baking dish on the center rack of the preheated oven.
Bake uncovered for 25 minutes until the casserole is hot throughout and bubbly at the edges.
Check the center of the casserole to make sure it is heated all the way through before removing from the oven.
Remove from the oven and let the casserole rest for 5 minutes before serving.
Scoop into bowls or onto plates and serve hot.