Preheat the oven to 375
In a dutch oven, heat the olive oil over medium heat. Add the chicken and cook on each side till browned, working in batches if necessary, about 7-10 minutes total.
Remove the chicken and set aside, and add a bit more oil if necessary.
Add the vegetables, onion and garlic and cook until the veggies are bright and a bit of their crispness is taken away. Transfer the vegetables to a plate and set aside.
Add the butter and rice to pan, and stir until coated.
Add the stock and bring to a boil over medium high heat.
If using precooked rice, just add the rice to the butter, and only add 1 cup of stock, no need to bring rice to a boil.
Add chicken and vegetables to the pan, nestled on top of the rice and place pan in oven.
Bake uncovered for 30 minutes, until liquid is absorbed and chicken is done.