In a 7-inch round cake or pizza pan insert, metal cake pan, or foil pan, combine the pears, brown sugar, cornstarch, and ½ teaspoon salt.

Toss until the pears are evenly coated in the sugar mixture.

In a mixing bowl, combine the remaining ½ teaspoon salt with the granulated sugar, butter, flour, and cocoa powder.

Pinch and press the butter into the other ingredients with your fingers until a sandy, shaggy crumble dough forms.

Stir in the chopped hazelnuts.

Sprinkle the crumble topping evenly over the pears.

Place the pan in the air fryer and cook at 320°F until the crumble is crisp and the pears are bubbling in the center, about 30 minutes.

Carefully remove the pan from the air fryer and serve the hot crisp in bowls, topped with ice cream or whipped cream if desired.