Preheat oven to 425 degrees Fahrenheit. Generously spray a 9x13 inch baking dish with cooking spray, ensuring all corners are well coated.
In a large skillet over medium-high heat, add ground beef and garlic salt. Cook, breaking meat into small crumbles, until completely browned with no pink remaining, about 6-7 minutes.
Carefully drain excess fat from the skillet, leaving just enough to keep the meat moist.
Spread uncooked rice evenly across the bottom of the prepared baking dish. Top with browned ground beef.
Pour French onion soup, beef consomme, and water over the rice and beef mixture. Stir gently until everything is well combined and rice is mostly submerged.
Slice butter into thin pats and arrange them evenly across the entire surface of the casserole.
Cover baking dish tightly with aluminum foil and bake for 30 minutes.
Remove foil carefully and continue baking uncovered for 30 minutes more until top is golden brown and rice is tender.
Remove from oven and let rest for 5 minutes. Fluff gently with a fork before serving hot.
