In a small bowl, combine the mayonnaise, freshly grated parmesan cheese, and herb and garlic seasoning. Mix until you have a uniform paste. Freshly grated parmesan works better than pre-shredded here because it distributes more evenly and creates a more cohesive crust when it melts.

Pat the salmon fillets dry with paper towels—this helps the mayo-parmesan mixture adhere better. Place the fillets skin-side down on a cutting board or directly in your air fryer basket. Generously spread the parmesan mixture from Step 1 evenly over the top of each fillet, using about 2 tablespoons per fillet. Make sure to coat all the way to the edges for even browning.

Preheat your air fryer to 380°F for 2 minutes. Arrange the coated salmon fillets in the basket in a single layer, skin-side down, making sure they don't overlap. Cook for 8 minutes—the salmon should be opaque and flake easily with a fork, and the parmesan crust should be golden brown. I find that skin-on fillets help keep the fish moist while the crust gets crispy. Serve immediately while the crust is still at its crispiest.