Season the chicken with salt and pepper. Heat olive oil in a large skillet or Dutch oven over medium-high heat. Sear the chicken for 4 to 5 minutes per side until golden brown. Remove from the skillet, let it rest briefly, then cut into bite-sized pieces. Set aside.

In the same skillet, melt butter over medium heat. Add the chopped onion and cook for about 2 to 3 minutes until it begins to soften. Stir in the minced garlic and cook for 30 seconds more. If using mushrooms, add them now and cook for an additional 3 to 4 minutes.

Add the rice to the skillet and stir constantly for 1 to 2 minutes to lightly toast it.

In a separate bowl, combine the cream of chicken soup, sour cream, garlic powder, onion powder, thyme, paprika, and cayenne (if using). Mix until smooth.

Pour the chicken broth and cream (or milk) into the skillet. Add the sauce mixture and stir until everything is well combined.

Return the diced chicken to the skillet, placing it into the rice mixture. Bring everything to a gentle simmer.

Reduce the heat to low, cover, and cook for 20 to 25 minutes, or until the rice is tender, the chicken is fully cooked (internal temperature of 165°F), and most of the liquid has been absorbed.

Remove the skillet from the heat and let it sit uncovered for 5 minutes.

Garnish with chopped parsley before serving. Spoon the creamy rice and sauce over the chicken to serve.