Prep the onions. Slice the onions into 1/4-inch rings. Separate the rings carefully so you get lots of thin loops. Pat them dry with paper towels to help the coating stick.

Set up the dredging station. In one shallow bowl, add the flour with a pinch of salt and pepper. In a second bowl, whisk the eggs and milk until smooth. In a third bowl, mix panko, Parmesan, cheddar, garlic powder, onion powder, smoked paprika, cayenne, and 1 teaspoon salt.

Coat the rings. Toss a handful of onion rings in the flour, shake off excess, dip into the egg wash, then press into the cheesy breadcrumb mix. Make sure each ring is well coated. Place on a parchment-lined baking sheet or air fryer tray.

Chill for better crunch. Pop the coated rings into the fridge for 10–15 minutes. This helps the crust set so it stays on during cooking.

Choose your method. For the oven, preheat to 425°F (220°C). For the air fryer, preheat to 375°F (190°C). Lightly spray or brush the rings with oil on both sides.

Bake or air fry. Oven: Bake for 12–16 minutes, flipping halfway, until deep golden and crisp. Add 1–3 extra minutes if needed.

Air fryer: Cook in a single layer for 8–10 minutes, flipping at 6 minutes, until crisp and browned. Work in batches.

Season and serve. While hot, sprinkle with a pinch of salt. Serve right away with your favorite dip.