1. Preheat your oven to 350°F (175°C).
2. In a large skillet over medium heat, melt the butter. Add the diced onion and sauté until translucent, about 3-4 minutes.
3. Add the uncooked rice to the skillet and stir to coat with the butter and onion mixture. Cook for an additional 2 minutes, allowing the rice to toast slightly.
4. Stir in the chicken broth, bringing it to a gentle simmer. Cover the skillet and reduce the heat to low, cooking for about 15 minutes until the rice is tender and has absorbed most of the liquid.
5. In a large bowl, combine the cooked chicken, sour cream, ranch seasoning, shredded cheese, frozen peas and carrots, and the cooked rice mixture. Season with salt and pepper to taste.
6. Transfer the mixture to a greased 9×13 inch baking dish. Spread evenly and sprinkle extra cheese on top if desired.
7. Bake in the preheated oven for 25-30 minutes, or until the top is golden and bubbly.
8. Remove from the oven and let it cool for a few minutes. Garnish with fresh parsley before serving, if desired.

This step-by-step process might remind you of the patience and rhythm my abuela instilled in me when we cooked together—taking the time to let flavors meld and develop into something wonderful.