01 - Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.
02 - In a skillet over medium heat, cook onion until translucent, about 3 minutes. Add ground beef, garlic powder, salt, and black pepper, then cook, breaking up meat, until browned. Drain excess fat.
03 - Stir in ketchup, yellow mustard, Worcestershire sauce, and optional pickles. Remove skillet from heat and allow mixture to cool slightly.
04 - Flatten each biscuit round. Place 1 tablespoon of the beef mixture and 1/2 tablespoon shredded cheddar cheese in the center. Top with a mozzarella cube.
05 - Fold dough over fillings, pinching all edges securely to enclose and form a ball. Arrange seam-side down on prepared baking sheet.
06 - Brush each bomb with beaten egg and evenly sprinkle with sesame seeds.
07 - Bake in oven for 15 to 18 minutes or until the surface is golden brown and cooked through.
08 - Allow bombs to cool for a few minutes before serving. Accompany with burger sauces for dipping, if desired.