Preheat the Air Fryer: Preheat your air fryer to the appropriate temperature for baking brownies, usually around 325°F (163°C).

Prepare the Batter: In a mixing bowl, cream together softened unsalted butter and granulated sugar until light and fluffy. Beat in eggs and vanilla extract until well combined. Gradually add the dry ingredients (all-purpose flour, cocoa powder, baking powder, and salt), mixing until just incorporated.

Bake in the Air Fryer: Pour the brownie batter into a greased and lined baking pan that fits comfortably in your air fryer basket. Carefully place the pan in the preheated air fryer and cook the brownies for 20-25 minutes, or until the edges are set and a toothpick inserted into the center comes out with a few moist crumbs attached.

Cool and Serve: Once baked, remove the brownies from the air fryer and let them cool in the pan for a few minutes. Then, transfer them to a wire rack to cool completely before slicing into squares. Enjoy your deliciously fudgy air fryer brownies!