Ingredients
Equipment
Method
- Position oven rack in the middle and preheat to 350°F (175°C), then line a 9x13 inch (23x33cm) light-colored aluminum pan with parchment paper leaving a 2-inch overhang on both long sides, and grease the two short exposed sides.
- Make the brownie batter: whisk together the melted cooled butter and neutral oil, then add the granulated sugar and whisk vigorously for 60 seconds until slightly thickened.
- Add the 2 eggs and 1 egg yolk to the brownie bowl one at a time, whisking fully after each addition, then whisk in the vanilla extract until the batter looks smooth and glossy.
- Sift the Dutch-process cocoa powder into the brownie bowl, add the flour and fine sea salt, then switch to a silicone spatula and fold gently for 15–20 strokes until no dry streaks remain — do not whisk.
- Make the cookie dough: in a separate bowl whisk together the melted cooled butter, packed brown sugar, and granulated sugar until smooth, then add the egg and egg yolk one at a time and whisk until glossy, then whisk in the vanilla extract.
- Add the flour, baking soda, and fine sea salt to the cookie dough bowl, switch to a silicone spatula, and fold until just combined, then fold in the semi-sweet chocolate chips with the final few strokes.
- Press approximately two-thirds of the cookie dough (about 400g) into an even layer across the bottom of the prepared pan, working it to the edges and corners until approximately ¼ inch (6mm) thick.
- Pour the entire brownie batter over the cookie dough base and spread evenly to the edges using an offset spatula, then drop the remaining cookie dough in rough tablespoon-sized pieces across the top and press reserved chocolate chips across the surface.
- Bake on the middle rack at 350°F (175°C) for 28–32 minutes, until the cookie dough pieces on top look golden amber and set, the brownie surface between them looks matte, and a toothpick inserted into the cookie dough portion comes out with moist crumbs — the brownie portion will still read fudgy and that is correct.
- Remove the pan from the oven and immediately scatter flaked sea salt across the entire top surface, then place on a wire rack and cool at room temperature for a minimum of 2 full hours before cutting.
- For cleanest cuts, refrigerate the cooled pan for 30 minutes, then lift the slab out using the parchment overhang, cut into a 4×4 grid for 16 bars using a sharp knife wiped clean between each cut, and serve at room temperature or slightly warm.
Notes
- Dutch-process cocoa: do not substitute natural cocoa — color and flavor will differ significantly.
- Butter: must be melted and cooled to room temperature before adding eggs — hot butter scrambles eggs and breaks the emulsion.
- Eggs: room temperature only — cold eggs cause the batter to look curdled and bake unevenly.
- Chocolate chips: semi-sweet 45–55% cacao recommended — milk chocolate makes bars very sweet, 70%+ gives a more intense result.
- Flour: weigh at 90g (brownie) and 150g (cookie dough) — scooping adds 30–40g and produces a cakey, dry result.
- Pan: light-colored aluminum only — dark pans overbrown the bottom cookie layer before the interior sets.
- Baking soda: freshness-check before using — drop ¼ tsp into hot water, it must bubble vigorously.
- Do not cut before 2 hours — the brownie center is still setting and will collapse when the knife goes through.
- Storage: airtight container at room temperature up to 4 days, refrigerator up to 7 days.
- Freeze baked: wrap individually in plastic wrap, freeze up to 3 months, thaw at room temperature 1–1.5 hours.
- Freeze unbaked: assemble in pan, cover tightly, freeze up to 1 month — bake from frozen in a cold oven adding 12–15 minutes.
- Make ahead: best made the day before — brownie flavor deepens overnight.
- Scaling: double requires two 9x13 pans — not one larger pan. Double all ingredients including baking soda exactly; leavening scales linearly here.
- Altitude (above 3,500ft): reduce baking soda by ⅛ tsp in the cookie dough layer.
- Allergens: contains gluten, dairy, eggs, soy (chocolate chips).
- Tip: refrigerate for 30 minutes after the 2-hour cool before cutting for the cleanest edges.