Prepare rice as directed. Prepare broccoli and corn together as directed.
As these are cooking, prepare cheese sauce - warm milk on medium heat. Break apart cheese slices and melt in milk. Add garlic powder, salt and pepper. Stir to avoid sticking.
Drain liquids from rice and veggies (leaving a little from veggies to add to cheese mixture). Mix all together. You can keep this dish warm in the oven without drying out as long as you prepared sauce semi-thin.