Instructions

• Preheat the oven to 350°F (175°C). Line an 8"x8" baking dish with two overlapping pieces of parchment paper so the paper hangs over two opposite sides; spray the parchment with cooking spray.
• In a medium saucepan over medium heat, melt ½ cup (1 stick) unsalted butter, stirring constantly with a wooden spoon. Continue cooking and stirring for several minutes until the butter smells nutty and small golden-brown bits form on the bottom of the pan (browned butter).
• Remove the pan from the heat and let the browned butter cool for 3–5 minutes so it is warm but not hot.
• In a large bowl, whisk the cooled browned butter into ¾ cup light brown sugar and ¼ cup granulated sugar until combined.
• Stir in 1 large egg, 2 teaspoons vanilla extract, and ½ teaspoon Kosher salt with a large spoon or spatula until smooth.
• Fold in 1 cup all-purpose flour until just combined; do not overmix.
• Fold in ½ cup white chocolate chips, ½ cup toffee bits, and ½ cup chopped walnuts until evenly distributed.
• Transfer the batter to the prepared baking dish and press it into an even layer using a spatula or clean hands.
• Bake until the top is lightly golden and a toothpick inserted into the center comes out clean, about 15–20 minutes. Start checking at 15 minutes to avoid overbaking.
• Let the blondies cool in the pan on a wire rack until firm enough to lift, about 20–30 minutes. Use the parchment overhang to lift the blondies from the pan, peel off the parchment, and place on a cutting board.
• Cut into squares. Serve warm or at room temperature with vanilla ice cream and warmed caramel sauce, if desired.