Brown the sausage in a large skillet over medium heat. Drain off any excess grease.
Add the rice, chicken broth, and diced tomatoes to the skillet. Bring to a boil, then reduce heat and simmer for 15-20 minutes, or until the rice is cooked through.
Stir in the cheddar cheese until melted.
Pour into a greased 9x13 inch baking dish and bake at 350°F (175°C) for 20-25 minutes, or until heated through and bubbly.
Notes
This casserole can be made ahead of time and reheated. Leftovers can be stored in the refrigerator for up to 3 days.