Preheat the oven to 425°F and prepare a 15×21-inch sheet pan or two smaller sheet pans.
Cut the broccoli into bite-size florets, thinly slice the onion, and slice the smoked chicken sausage into coins.
In a small bowl, combine the garlic powder, Italian seasoning, onion powder, chicken bouillon powder, salt, and pepper; stir and remove 2 teaspoons of the mixture to reserve.
Place the broccoli, sliced onion, and sausage on the sheet pan. Drizzle with the olive oil and sprinkle with the remaining seasoning mixture (not the reserved 2 teaspoons). Toss with your hands to coat and spread in a single layer, avoiding overlap so the vegetables roast.
Roast in the preheated oven for 13–15 minutes, until broccoli is tender and edges are lightly browned.
While the pan roasts, break up the Ready Rice packets by kneading them without opening; if using cooked rice, have 2 cups ready. Do not microwave the unopened packets.
Remove the sheet pan from the oven, add the rice and the reserved 2 teaspoons of seasoning on top, then toss everything together with a large spatula and spread into one even layer.
Return the pan to the oven for 2 minutes to heat the rice, then remove and toss once more to combine.
Sprinkle the shredded sharp cheddar evenly over the mixture and return to the oven for 2 minutes, or until the cheese is melted.
Remove from the oven, taste and adjust seasoning with extra salt and pepper if desired, garnish with fresh parsley if using, and serve.