Start by gathering all your ingredients. Dice the chicken breast into bite-sized pieces and slice the mushrooms. Make sure the rice is cooked and ready to go.
In a large skillet, heat the olive oil over medium heat. Add the diced chicken breast and season with salt, pepper, garlic powder, and onion powder. Cook until the chicken is browned and cooked through, about 5-7 minutes. Remove the chicken from the skillet and set it aside.
In the same skillet, add the sliced mushrooms. Sauté them until they are golden brown and tender, about 4-5 minutes.
Pour in the heavy cream and chicken broth into the skillet with the mushrooms. Stir to combine, scraping up any bits from the bottom of the pan. Bring the mixture to a gentle simmer, allowing it to thicken slightly for about 3-4 minutes.
Return the cooked chicken to the skillet, stirring to coat it in the creamy sauce. Gently fold in the cooked rice until it is evenly distributed.
Pour the creamy chicken and mushroom mixture into a baking dish. Spread it out evenly to ensure even cooking.
Top the mixture with the shredded mozzarella cheese. Preheat your oven to 375°F (190°C) and bake for 20-25 minutes, or until the cheese is bubbly and golden brown.
Once out of the oven, let the dish cool for a few minutes before serving. Serve hot, straight from the oven, with a side salad or crusty bread.