01 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
02 - In a skillet over medium heat, cook diced onion until translucent, about 3 minutes. Add the ground beef, garlic powder, salt, and pepper. Cook until the beef is browned, then drain any excess fat.
03 - Stir ketchup, yellow mustard, Worcestershire sauce, and chopped pickles into the cooked beef. Remove skillet from heat and allow mixture to cool slightly.
04 - Flatten each biscuit round. Place 1 tablespoon of beef mixture and 1/2 tablespoon shredded cheddar cheese in the center of each round. Top with a mozzarella cube.
05 - Enclose fillings by gathering and pinching edges of dough to seal. Shape into a smooth ball, seam side down, and arrange on prepared baking sheet.
06 - Brush each dough ball with beaten egg and sprinkle with sesame seeds.
07 - Bake for 15 to 18 minutes or until the exterior is golden brown and crisp.
08 - Let cool slightly before serving. Provide burger sauces for dipping if desired.