In a mixing bowl, whisk together the gluten-free flour blend, cocoa powder, sugar, baking powder, and salt until well combined.

In a separate bowl, beat the eggs until slightly frothy. Add the melted butter (or coconut oil) and vanilla extract, and mix until smooth.

Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix.

Preheat your air fryer to 320°F (160°C) for a few minutes.

Lightly grease a square baking pan that fits into your air fryer basket with cooking spray or oil.

Pour the brownie batter into the prepared baking pan, spreading it evenly with a spatula.

Place the baking pan into the preheated air fryer basket and cook for 20-25 minutes, or until a toothpick inserted into the center comes out with moist crumbs.

Once cooked, remove the brownies from the air fryer and allow them to cool in the pan for a few minutes. Then, carefully transfer them to a wire rack to cool completely before slicing and serving.