Directions

1. Preheat oven to 350 degrees. Brush an 8-inch square baking pan with butter; line pan with a piece of parchment paper, leaving a 2-inch overhang on two sides. Butter paper.
2. In a large bowl, whisk butter and sugars until smooth. Whisk in egg and vanilla. Add flour and salt; mix just until moistened (do not overmix). Fold in 1/2 cup each chocolate chips and walnuts. Transfer batter to prepared pan; smooth top. Sprinkle with remaining chocolate chips and walnuts.
3. Bake until top is golden brown and a toothpick inserted into the center comes out clean, 40 to 45 minutes. Set pan on a wire rack, and let cool completely. Using parchment overhang, lift cake from pan and transfer to a cutting board; cut into 16 squares. Store blondies in an airtight container at room temperature, up to 2 days.