Prep the pan and air fryer: Line a 6–7-inch square or 7–8-inch round pan with parchment, leaving overhang for easy lifting. Spray lightly with nonstick spray. Preheat the air fryer to 320°F (160°C) for 3–5 minutes if your model allows.

Melt butter and chocolate: In a saucepan over low heat, melt the butter with 3/4 cup chocolate, stirring until smooth. Or microwave in 20–30 second bursts, stirring between each. Let cool 2–3 minutes.

Whisk sugars and eggs: In a medium bowl, whisk granulated sugar, brown sugar, and eggs for about 45–60 seconds until slightly thickened and lighter. Whisk in vanilla. This step helps create that glossy top.

Combine wet ingredients: Slowly whisk the melted chocolate-butter mixture into the egg mixture until smooth.

Add dry ingredients: Sift or whisk together flour, cocoa, salt, and espresso powder (if using). Fold into the batter with a spatula until just combined. Do not overmix.

Fold in extra chocolate: Stir in the remaining 1/2 cup chocolate chips for extra pockets of gooeyness.

Fill the pan: Spread the batter evenly in the prepared pan. Smooth the top and tap lightly on the counter to remove air bubbles.

Air fry: Place the pan in the air fryer basket. Cook at 320°F (160°C) for 18–22 minutes. Start checking at 16 minutes. A toothpick should come out with moist, fudgy crumbs, not wet batter.

Cool for clean slices: Let brownies cool in the pan for at least 30–40 minutes. For extra neat edges, chill 20 minutes before slicing.

Slice and serve: Lift out using the parchment. Cut into 8–9 squares. Enjoy warm, or top with ice cream and a pinch of flaky salt.