Prepare the Oven: Heat the oven to 325 F (165 C) and grease a 2-quart baking dish.

Cook the Beef and Aromatics: Heat the oil in a large skillet over medium-high heat. Add the ground beef; break it into smaller pieces and cook undisturbed for 4 minutes. Add the onion and bell pepper and continue cooking, stirring, for 4 to 5 minutes longer or until the beef is no longer pink and the onion is translucent. Drain excess grease and add the remaining ingredients.

Bake: Spoon the bean mixture into the prepared baking dish and bake for 30 minutes or until hot and bubbling.

Serve: Garnish with green onions or cheese if desired, and enjoy!