01 - Set oven temperature to 350°F and allow to preheat fully.
02 - Heat a large nonstick skillet over medium-high. Add ground beef and diced onion, breaking beef apart as it cooks. Sauté until beef is thoroughly browned and onions are softened, approximately 7–8 minutes.
03 - Stir in chopped garlic, cheddar soup, cream of mushroom soup, 0.5 cup milk, salt, and black pepper. Mix until completely blended and smooth. Incorporate 1 cup of shredded cheddar cheese, stirring until melted. Remove skillet from heat.
04 - Lightly coat a 9 x 13-inch baking dish with cooking spray. Spread beef mixture evenly in the dish, then sprinkle over the remaining 1 cup shredded cheddar cheese.
05 - Empty Cheddar Bay Biscuit mix into a large mixing bowl, reserving the seasoning packet. Add 1 cup shredded cheddar cheese and 2 cups milk; mix until batter is smooth and lump-free.
06 - Pour the prepared biscuit batter evenly over the beef layer in the baking dish. Transfer to the oven and bake for 50 to 55 minutes, until biscuit topping is golden brown throughout.
07 - Combine melted butter with the reserved Cheddar Bay Biscuit seasoning packet, mixing thoroughly.
08 - Remove the dish from the oven. Immediately brush hot biscuit topping with the butter-seasoning mixture. Allow to stand 5 minutes before garnishing with fresh chopped parsley and serving.