01 - Peel onions and slice into thick 1/2-inch rings. Carefully separate into individual rings, selecting the largest intact rings for stuffing. Set aside.
02 - Arrange three shallow bowls: place flour in the first, beaten eggs in the second, and combine panko breadcrumbs, smoked paprika, garlic powder, salt, and pepper in the third bowl.
03 - Heat olive oil in a skillet over medium heat. Add ground beef, salt, pepper, and Worcestershire sauce. Cook, breaking up meat, until browned throughout, approximately 5–7 minutes. Remove from heat and allow to cool slightly.
04 - Stir diced pickles, tomatoes, shredded cheddar cheese, ketchup, and mustard into the cooled beef mixture until evenly combined.
05 - Fill each large onion ring with the cheeseburger mixture, pressing gently to create a compact filling that holds its shape within the ring.
06 - Dredge each stuffed ring in flour, shaking off excess. Dip into beaten eggs, then press firmly into seasoned panko mixture to coat completely and evenly.
07 - Heat vegetable oil in a deep fryer or heavy pot to 350°F. Fry stuffed rings in batches for 2–3 minutes per side until golden brown and crispy. Transfer to paper towels to drain excess oil.
08 - Serve immediately while hot and crispy, accompanied by your preferred burger sauce or dipping condiment.