Line a 6" circular cake pan with parchment paper.
In a medium mixing bowl, stir together the flour, cocoa powder, and salt. Set aside.
1/3 cup (42 grams) flour, 1/4 cup (29 grams) Dutch-process cocoa powder, 1/16 teaspoon salt
In a large mixing bowl, stir together the melted oil, sugar, and vanilla extract. Once combined, add the egg and stir just until combined.
1/4 cup + 2 teaspoons (65 grams) coconut oil, 1/2 cup (100 grams) granulated sugar, 1 teaspoon vanilla extract, 1 large egg
Add the dry mixture to the wet and stir just until almost no streaks of flour remain. Do not overmix! Fold in 1/4 cup chocolate chips (ignore the quantity below - it's a technical issue I can't fix).
1/4 cup (43 grams) chocolate chips
Preheat the air fryer to 340 °F (170 °C).
Pour the batter into the prepared pan and sprinkle mini chocolate chips on top (ignore the quantity below - it's a technical issue I can't fix). Bake for 10-14 minutes or until the brownies have formed a thin crust and appear set in the middle. A toothpick inserted into the center will come out wet. A toothpick inserted into the sides will come out with some moist crumbs on it, but not totally raw batter. The brownies will continue to bake as they sit in the pan and will firm up as they cool.
1/4 cup (43 grams) chocolate chips
Let cool completely and then cover and store at room temperature for up to 4 days. You can also refrigerate them (for up to a week) to give them a fudgier texture.