Extra crunchy topping: Crisp the topping onions before you add them. In the air fryer, spread them in an even layer in the basket and air fry at 375°F for 1 to 2 minutes, shaking the basket halfway through. In the oven, spread them on a baking sheet and bake at 400°F for 3 to 5 minutes. Either way, watch them closely so they don't scorch.