- Preheat your oven to 375°F (190°C). 
- In a large skillet, heat the olive oil over medium heat. Add the diced onion and garlic, sautéing until the onion is translucent, about 3-4 minutes. 
- Add the ground chicken to the skillet, cooking until browned and fully cooked, about 5-7 minutes. 
- Stir in the cooked rice, diced pineapple, teriyaki sauce, black pepper, and salt. Cook for an additional 2-3 minutes until everything is heated through. 
- While the filling is cooking, slice the tops off the bell peppers and remove the seeds. 
- Place the bell peppers upright in a baking dish. Spoon the chicken and pineapple mixture into each pepper, packing it down gently. 
- Cover the baking dish with aluminum foil and bake for 25 minutes. 
- Remove the foil and bake for an additional 10 minutes, until the peppers are tender. 
- Garnish with chopped green onions before serving.