Cook the rice and set aside.
Pre-heat oven to 375 degrees.
Heat a large skillet over medium heat. Add the olive oil if you are using ground turkey. Add the meat and using a wooden spoon, start to cook and crumble the turkey or beef. If you are using the beef you will probably want to drain some of the grease.
Add the onion and cook until the meat is almost done. Put in the salt, pepper, red pepper flakes, Italian Seasoning and the bell peppers. Cook for 1 - 2 minutes.
Next, add the diced tomatoes, tomato sauce, and about 1/2 can of water. Bring this mixture to a boil and cook for a few minutes.
Spoon the rice into the sauce and stir well. Pour the mixture into a 13" x 9" baking dish that has been coated with non-stick spray.
Bake for about 20 minutes, or until bubbly and the cheese has completely melted and started to brown.
Cool slightly and serve.