Loaded Blondies

Preheat an oven to 350°F (180°C). Line an 8-inch (20-cm) square baking pan with parchment paper, letting it overhang on two sides by at least 1 inch (2.5 cm). Spray the parchment with nonstick cooking spray.

In a small saucepan over medium heat, melt the butter, swirling the pan occasionally to ensure the butter is melting evenly, until it starts to foam, about 3 minutes. Continue to cook, swirling the pan occasionally, until the butter turns deep golden and smells nutty, 5 to 7 minutes more. Transfer the brown butter to a large heatproof bowl and let cool completely, about 15 minutes.

Meanwhile, in a small bowl, whisk together the flour, kosher salt, baking powder and baking soda. Set aside.

Add the brown sugar to the bowl with the cooled brown butter and stir until thoroughly combined. Whisk in the egg and vanilla. Add the flour mixture and stir until no streaks of flour remain. The batter will be thick. Using a rubber spatula, fold in half each of the chocolate chips, chocolate chunks and walnuts.

Transfer the batter to the prepared pan and spread evenly. Drizzle with the caramel sauce (if the sauce is too thick, microwave in 10-second increments until pourable). Top with the remaining chocolate chips, chunks and walnuts, pressing them down slightly into the batter. Sprinkle generously with flaky sea salt.

Bake until the blondies are deep golden brown and a toothpick inserted into the center comes out with only a few moist crumbs attached, 35 to 38 minutes. Transfer the pan to a wire rack and let cool completely in the pan. Using the overhanging parchment, transfer the brownies to a cutting board. Remove the parchment paper and use a sharp knife to cut into 12 bars. Serve immediately, or store in an airtight container at room temperattur for up to three days. Makes 12 blondies.

Williams Sonoma Test Kitchen