Peel and slice the sweet onion into ½-inch thick rings. Separate the rings and match them with mozzarella sticks, cutting the cheese sticks as needed to fit inside each ring. Freeze for 30 minutes.
Prepare three shallow bowls: one with ½ cup of flour, another with whisked eggs and buttermilk, and the third with remaining flour, cornmeal, panko, crushed Corn Chex, salt, and pepper.
Dip each onion-mozzarella combo into the flour, then the egg mixture, then the breadcrumb mix, pressing to coat well. Place them on a lined baking sheet.
Spray lightly with nonstick cooking spray and bake at 400°F for 12-15 minutes, flipping halfway, until golden brown and crispy.
Serve hot with marinara sauce or ranch dressing for dipping. Enjoy!
Notes
For extra crunch, double coat the rings by dipping them in the flour and egg mixture twice. Freezing before baking helps keep the cheese from melting too quickly.