Step 1

Preheat air fryer to 320℉. Coat a 6-inch round cake pan with cooking spray. Line the pan bottom with parchment or wax paper. Flour the pan, tapping out excess.

Step 2

Combine flour, cocoa, baking powder, baking soda and salt in a small bowl. Whisk buttermilk, applesauce, oil, espresso powder and vanilla in another small bowl.

Step 3

Place egg in a medium bowl; beat with an electric mixer on low speed. Gradually add sugar. Increase the mixer speed to high and continue beating until the mixture is thick and pale, about 2 minutes.

Step 4

Alternately fold the dry ingredients and the buttermilk mixture into the egg mixture with a rubber spatula, making 3 additions of dry ingredients and 2 additions of buttermilk mixture. Fold in chocolate.

Step 5

Pour the batter into the prepared pan and place in the air-fryer basket. Cook until a toothpick inserted in the center comes out clean, about 25 minutes. Let cool in the pan on a wire rack for 10 minutes. Remove from the pan. Remove parchment (or wax) paper. Let cool completely on the rack.

Step 6

Serve the cake topped with confectioners' sugar (and/or cocoa powder) and mixed berries.