1. Preheat your oven to 375°F (190°C). Grease a casserole dish and set aside.
2. In a skillet, brown the ground beef with the diced onion over medium heat until fully cooked. Drain any excess grease.
3. Stir in tomato sauce, garlic powder, paprika, salt, and pepper. Simmer for 5 minutes, then pour the mixture into the prepared casserole dish.
4. Sprinkle 1 1/2 cups of shredded cheddar cheese over the beef mixture.
5. In a bowl, mix the biscuit mix with milk until just combined. Drop spoonfuls of the biscuit batter on top of the cheese.
6. Bake for 20-25 minutes, or until the biscuits are golden brown and cooked through.
7. Sprinkle with remaining cheddar cheese and bake for another 5 minutes until melted.