Preheat the oven to 350°F. Lightly grease a 9x13-inch baking dish with nonstick cooking spray and set aside.

Heat the olive oil in a large skillet over medium heat. Add the diced onion and bell peppers and cook for about 5 minutes, stirring occasionally, until they begin to soften. They don't need to be fully cooked since they'll continue cooking in the oven. Season lightly with salt and pepper. During the last minute of cooking, stir in the garlic and cook until fragrant.

In the prepared baking dish, combine the tomato sauce, diced tomatoes, uncooked Instant Rice, chicken broth, and half of the salt, pepper, garlic powder, and Italian seasoning. Stir in the sautéed onions and peppers.

Using the same skillet, cook the ground beef over medium-high heat, breaking it into crumbles as it cooks, until no longer pink, about 8–9 minutes. Drain any excess grease if needed. Season with the remaining salt, pepper, garlic powder, and Italian seasoning.

Add the cooked ground beef to the baking dish and stir until everything is evenly combined.

Cover the baking dish tightly with aluminum foil and bake for 35–45 minutes, or until the rice is tender and has absorbed most of the liquid. Since Instant Rice cooks quickly, begin checking for doneness at the 35-minute mark.

Remove the foil and sprinkle the shredded cheese evenly over the top, if using. Return the dish to the oven and bake uncovered for an additional 5–10 minutes, or until the cheese is melted and bubbly.

Let the casserole rest for 5 minutes before serving. Scoop onto plates and enjoy!