Preheat the oven to 375°F (190°C).
Heat olive oil in a large oven-safe skillet or casserole dish over medium heat.
Add diced onion and cook for 3-4 minutes until softened.
Add minced garlic and cook for 30 seconds until fragrant.
Add the chicken pieces to the skillet and cook for 5 minutes, stirring occasionally, until lightly browned but not fully cooked through.
Add the uncooked rice, diced carrots, diced bell pepper, and frozen peas to the skillet. Stir to combine.
Pour in the chicken broth and add dried thyme, dried oregano, salt, and black pepper. Stir well.
Bring the mixture to a gentle simmer on the stovetop.
Cover the skillet or casserole dish tightly with a lid or aluminum foil.
Transfer the dish to the preheated oven and bake for 40 minutes, until the rice is tender and the chicken is cooked through.
Remove the casserole from the oven and carefully remove the lid or foil.
Sprinkle shredded cheddar cheese evenly over the top of the casserole.
Return the casserole to the oven uncovered and bake for an additional 5 minutes, or until the cheese is melted and bubbly.
Remove from the oven and let the casserole rest for 5 minutes before serving.