Start by preheating the air fryer to 315F for 5 minutes. Grease a 6-inch round cake pan and set it aside.
While the air fryer is preheating, mix the flour, cocoa powder, salt, and baking powder in a small bowl and set aside.
In a separate small bowl, melt the butter and chocolate chips together. in the microwave in 30-second increments. Stir in between every time. Set aside.
In a large bowl, whisk the egg, granulated sugar, and vanilla together until light in color and fluffy.
Mix in the melted butter and chocolate mixture until combined, then gently fold in the flour until it disappears. Don't overmix. Pour the brownie batter into the prepared cake pan and bake in the preheated air fryer at 315F for 15 minutes.
Pull out your brownie using oven mitts and let it cool in the cake pan for 10 minutes to set.
Top the brownie with ice cream, whipped cream or enjoy as is.
Note- The thing about air fryer though is that they vary greatly in temperature. So when making your brownies, check for doneness by inserting a toothpick in the center of the brownie about ⅔ of the way into baking them. If the toothpick comes out mostly dry with only a few wet crumbs you'll know your brownies are done baking!