01 - Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.
02 - In a skillet over medium heat, sauté onion until translucent, about 3 minutes. Add ground beef, garlic powder, salt, and pepper. Cook until beef is browned and crumbly. Drain excess fat.
03 - Stir in ketchup, yellow mustard, Worcestershire sauce, and chopped pickles. Remove from heat and let mixture cool slightly.
04 - Flatten each biscuit round. Place 1 tablespoon beef mixture and 1/2 tablespoon shredded cheddar cheese in the center of each. Top with one mozzarella cheese cube.
05 - Fold dough around filling and pinch the edges to seal tightly, forming a ball. Place seam side down on the prepared baking sheet.
06 - Brush each ball with beaten egg and sprinkle with sesame seeds.
07 - Bake for 15 to 18 minutes or until the dough is golden brown.
08 - Allow to cool slightly before serving. Enjoy with additional burger sauces if desired.