Preheat oven to 425°F.
Use a paring knife to cut a circle around the stem of the pepper and remove it. Cut the peppers in half from stem to end, creating 6 pepper halves. Place the peppers cut side down on the cutting board and gently tap them to loosen any remaining seeds.
3 large bell peppers
Arrange them in a 9x13-inch baking pan, cut sides up. Drizzle the peppers with olive oil and sprinkle them with salt and pepper.
1-2 tablespoons olive oil
Bake for 20 minutes or until the peppers just begin to soften.
While the peppers cook, add the ground beef and onion to a large skillet over medium-high heat. Cook, breaking up the meat until the meat is cooked through, and the onions are softened. Drain off any excess grease.
1 pound 80% lean ground beef, ½ yellow onion
Add in the garlic salt, chili powder, cumin, and oregano, and cook for another 60 seconds, or until the spices are fragrant.
2 cloves garlic, 1 teaspoon kosher salt, 1½ teaspoons chili powder, 1 teaspoon ground cumin, ¼ teaspoon dried oregano
Stir in the rice, and tomato sauce. Bring to a simmer and cook until the sauce thickens, about 1-2 minutes.
1 cup cooked white rice, 15 ounces tomato sauce
Stir in ¾ cup of the cheese until it melts.
1½ cups shredded mozzarella cheese
Spoon the filling into the peppers and top with the remaining cheese.
Bake for 10-15 minutes until the cheese has melted and the peppers are tender. Garnish with green onion and serve.
1 green onion