01 - Separate onion slices into individual rings. In three separate bowls, arrange: flour mixed with smoked paprika, garlic powder, and salt; whisked eggs; and panko breadcrumbs.
02 - Dredge each onion ring in flour mixture, dip into beaten eggs, then press into panko breadcrumbs to coat thoroughly. Heat vegetable oil in a deep skillet over medium-high heat. Fry onion rings in batches until golden brown and crispy, approximately 2-3 minutes per batch. Transfer to paper towels to drain excess oil.
03 - Heat a non-stick skillet over medium heat. Place one flour tortilla in the skillet. Sprinkle evenly with one-quarter of the shredded cheddar and mozzarella cheese blend.
04 - Arrange several fried onion ring chips over the cheese layer. Drizzle with 2 tablespoons sour cream and sprinkle with fresh chives if using. Place second tortilla on top to create a sandwich.
05 - Cook quesadilla for 2-3 minutes until bottom tortilla is golden brown and cheese begins to melt. Carefully flip and cook an additional 2 minutes until cheese is completely melted and second side is golden.
06 - Remove quesadilla from skillet and let cool for 1 minute. Cut into 4-6 wedges. Serve immediately with salsa, guacamole, and additional sour cream on the side.