01 - Preheat the oven to 400°F and line a baking sheet with parchment paper.
02 - In a skillet over medium heat, sauté the onion until translucent, about 3 minutes. Add ground beef, garlic powder, salt, and black pepper, cooking until browned. Drain excess fat.
03 - Stir in ketchup, yellow mustard, Worcestershire sauce, and finely chopped pickle. Remove from heat and allow to cool slightly.
04 - Flatten biscuit rounds. Place 1 tablespoon of beef mixture and 1/2 tablespoon shredded cheddar cheese in the center of each round, then top with a cube of mozzarella.
05 - Fold biscuit dough around the filling, pinching the edges firmly to enclose and shape into a ball. Place seam-side down on prepared baking sheet.
06 - Brush each assembled bomb with beaten egg and sprinkle with sesame seeds.
07 - Bake in preheated oven for 15 to 18 minutes or until golden brown.
08 - Let cool slightly before serving. Accompany with ketchup, mustard, or your preferred sauce.