Preheat the oven to 375°F (190°C).
Heat olive oil in a large oven-safe skillet or casserole dish over medium heat.
Add the diced onion and cook for 3-4 minutes until translucent.
Add the minced garlic and cook for 1 minute until fragrant.
Add the chicken pieces to the skillet and cook for 5-6 minutes until lightly browned but not fully cooked through.
Stir in the rinsed rice, frozen peas, frozen diced carrots, and frozen corn kernels.
Pour in the chicken broth and stir to combine all ingredients evenly.
Add the sour cream, dried thyme, dried parsley, salt, and black pepper. Stir well to incorporate the sour cream into the mixture.
Bring the mixture to a gentle simmer on the stovetop.
Sprinkle the shredded cheddar cheese evenly over the top.
Transfer the skillet or casserole dish to the preheated oven.
Bake uncovered for 35-40 minutes, or until the rice is tender and the liquid is absorbed.
Remove from the oven and let the casserole rest for 5 minutes before serving.