
Spray the inside of your crockpot with non-stick cooking spray to prevent the cheese and rice from sticking to the sides.
Add the instant white rice, vegetable broth, and frozen chopped broccoli to the slow cooker.
In a separate bowl, whisk together the cream of celery soup, garlic powder, onion powder, and 1½ cups shredded cheese.
Pour the creamy mixture over the rice and broccoli. Stir gently until everything is well combined.
Cover the crockpot with the lid and cook on LOW for 3 to 4 hours or on HIGH for 2 to 2½ hours.
Stir once or twice during cooking.
Because cooking times can vary slightly by appliance, check the casserole toward the end of the cooking window to ensure the rice is completely tender.
Give the casserole a gentle stir. Sprinkle the additional half-cup of shredded cheddar cheese evenly over the top. Cover with the lid for 3 to 5 minutes to let the cheese melt completely. If you are using crushed buttery crackers for a crunchy finish, sprinkle them over the melted cheese right before moving to the next step.
Turn your slow cooker to the "Warm" setting and remove the lid entirely. Let the casserole sit uncovered for 10 to 15 minutes before serving. This crucial rest period allows the cheese sauce to cool slightly and thicken up while giving the instant rice a final chance to pull in any remaining savory moisture.