Preheat a 7-inch baking dish for 5 minutes in the air fryer at 375℉ on baking mode.
Meanwhile, add eggs, melted butter, oil, and vanilla to a medium-sized mixing bowl. Whisk ingredients well to combine.
Add sugar and whisk until the mixture is creamy, with little to no grains of sugar remaining.
Add cocoa powder, flour, and baking powder to the bowl and stir to combine, until the flour and cocoa powder are fully incorporated into the mixture.
Gently fold in the chocolate chips. Pour batter into the preheated baking dish in the air fryer and cook for 15-20 minutes at 375℉. To ensure that brownies are done baking, insert a toothpick into the center of the pan. If it comes out dry, or with a few moist crumbs, remove brownies from air fryer.
Notes
Avoid over mixing the batter. Stop stirring when there are no visible streaks of flour.
Let them cool slightly before cutting. This makes it easier to remove the brownies from the pan, and helps prevent the servings from crumbling and falling apart.