Preheat the oven to 350ºF. Chop the onion, green bell pepper, and red bell pepper.
Add the olive oil to a medium-sized skillet and cook over medium heat, then add the onions and bell peppers. Stir while cooking for about 5 minutes.
Add the beef, chili powder, cumin, salt, and peppers and cook for about 5 minutes, until the beef is no longer pink. Add the garlic and cook for 1 minute.
Stir in the rice and yogurt.
Layer the casserole in a baking dish and bake for 15 minutes uncovered.