Preheat oven to 350 degrees F (175 degrees C). Spray 2-quart baking dish with non-stick cooking spray.
Prepare rice according to package directions.
Melt butter in a skillet over medium to medium-high heat. Add mushrooms and saute until they release some moisture and begin to brown, 4 to 5 minutes. Remove mushrooms from pan.
Heat 2 tablespoons olive oil over medium heat in the same skillet. Saute chicken pieces until browned. Season with salt, pepper, and garlic powder to taste.
Combine the rice, chicken, mushrooms, and 3/4 of the jar of Alfredo sauce in the prepared baking dish. Mix well, and then spread remaining sauce over the top. Sprinkle crushed crackers evenly over casserole and drizzle 1 tablespoon melted butter over top.
Bake until heated through and topping is golden, about 30 minutes. Garnish with parsley.