Heat a large skillet over medium-high heat. Add ground beef and diced onion, breaking the beef into small crumbles. Cook 6-8 minutes until beef is browned and onion is softened. Drain excess grease completely. Season with garlic powder, Worcestershire sauce, salt, and black pepper. Stir to combine. Transfer beef mixture to a plate and let cool completely to room temperature, about 10-15 minutes. This cooling step is critical to prevent the dough from getting melty.

While beef cools, preheat oven to 375°F and line a baking sheet with parchment paper. Open the can of biscuit dough and separate into individual biscuits. Cut each biscuit in half to make 16 pieces, or use 12 biscuits whole for larger bombs. Flatten each piece into a 3-4 inch circle using your hands or a rolling pin. Cut cheddar cheese into small cubes, about half an inch each.

Place a flattened biscuit circle in your palm. Add one tablespoon of cooled beef mixture to the center. Place one cheese cube on top of the beef. Don't overfill or they will explode. Gather the edges of the dough up and over the filling, bringing all sides to the center. Pinch the seams together tightly with your fingers, making sure there are absolutely no gaps. Pinch again to be sure. Roll the sealed ball gently between your palms to smooth it out. Place seam-side down on the prepared baking sheet. Repeat with remaining dough and filling.

In a small bowl, mix melted butter with minced garlic, grated parmesan, Italian seasoning, and chopped parsley. Brush this garlic butter mixture generously over the top and sides of each bomb. Sprinkle with sesame seeds if using. Bake for 12-15 minutes until golden brown on top. Let cool 5 minutes before serving so the cheese inside sets slightly. Serve with ketchup, mustard, or special sauce for dipping.