Double Chocolate Walnut Brownie Recipe

Prepare pan

Preheat the oven to 175°C (350°F). Lightly grease a 9x9-inch (23x23 cm) square baking pan with 1 tablespoon butter or oil. Line the pan with parchment paper, leaving an overhang on two sides to lift brownies out later; grease the parchment lightly.

Melt chocolate and butter

Place the 170 g chopped chocolate and 115 g butter in a heatproof bowl set over a pot of barely simmering water (double boiler) or microwave in 20–30 second bursts, stirring between each, until melted and smooth. Remove from heat and let cool for 3–5 minutes.

Combine sugars and eggs

In a medium bowl, whisk together 1 cup granulated sugar and 1/4 cup packed light brown sugar. Add the 2 large eggs and 1 teaspoon vanilla extract and whisk vigorously until mixture is glossy and slightly thickened, about 1–2 minutes.

Incorporate chocolate into egg mixture

Slowly pour the slightly cooled melted chocolate-butter mixture into the egg-sugar mixture while whisking constantly to temper the eggs and create a smooth, shiny batter.

Add dry ingredients

Sift or whisk together 3/4 cup all-purpose flour, 1/4 cup unsweetened cocoa powder, and 1/2 teaspoon fine salt. Fold the dry ingredients into the chocolate mixture with a rubber spatula just until no streaks of flour remain. Avoid overmixing; batter should be thick and glossy.

Stir in walnuts and chips

Fold in 1 cup toasted, roughly chopped walnuts and 1/2 cup semisweet chocolate chips, reserving a small handful of chips and walnuts for sprinkling on top.

Transfer the batter into the prepared pan and smooth the top with an offset spatula. Sprinkle the reserved chocolate chips and walnut pieces evenly over the surface, and lightly press them into the batter. If desired, sprinkle 1/4 teaspoon coarse sea salt over the top for contrast.

Bake in the preheated 175°C (350°F) oven for 22–28 minutes. Begin checking at 20 minutes: the edges should be set and a thin crust will form on top, but the center should still be slightly soft and a toothpick inserted into the center will come out with a few moist crumbs (not raw batter) for fudgy brownies. For cake-like brownies, bake 2–4 minutes longer.

Remove the pan from the oven and let the brownies cool on a wire rack for at least 30 minutes to set. Use the parchment overhang to lift the brownies from the pan, then transfer to a cutting board and cut into 9 or 12 squares with a sharp knife. Serve at room temperature; store airtight at room temperature up to 3 days or refrigerate up to 7 days.