Step 1: Preheat your oven to 375°F (190°C). Line a large baking sheet with parchment paper or lightly grease it.
Step 2: In a medium skillet, cook the ground beef and finely chopped onion over medium heat until the beef is fully browned and the onions are soft (about 6-8 minutes). Drain any excess fat thoroughly.
Step 3: Stir in the salt, black pepper, 1 tsp garlic powder, ketchup, and yellow mustard. Cook for an additional 2-3 minutes, then remove from heat and let the mixture cool slightly.
Step 4: Separate each biscuit from the can and flatten it into a 4-inch circle using your hands or a rolling pin.
Step 5: Place about 2 tablespoons of the cooled beef mixture in the center of each flattened biscuit. Top the beef with 2 tablespoons of shredded cheddar cheese.
Step 6: Carefully gather the edges of the biscuit dough up and over the filling, pinching them tightly together to seal, forming a smooth, round ball. Place each bomb seam-side down on your prepared baking sheet.
Step 7: In a small bowl, whisk together the melted unsalted butter, 1 tsp garlic powder, and grated Parmesan cheese.
Step 8: Generously brush this garlic-Parmesan butter mixture over the top of each dough ball, ensuring full coverage.
Step 9: Bake in the preheated oven for 15-18 minutes, or until the tops are golden brown and slightly crispy.
Step 10: If desired, sprinkle with fresh chopped parsley immediately after baking. Let cool for a few minutes before serving warm.