Cut the avocados in half, remove the pits, and scoop out the flesh with a spoon. Slice each half lengthwise into 5 even pieces. Slightly firm avocados work best because they don’t turn mushy during cooking.
In one bowl, combine panko breadcrumbs, Parmesan, and black pepper. In another bowl, whisk the eggs. Dip each avocado slice in the egg first, then coat with the breadcrumb mixture, pressing lightly to ensure it sticks.
Spray the air fryer basket lightly with nonstick spray. Place avocado slices in a single layer without touching. Air fry at 350°F for 3 minutes per side until golden brown and crispy. Repeat with remaining batches. Alternatively, bake at 350°F for 10–12 minutes.