Recipe from Cookies for Kids' Cancer: All the Good Cookies (Houghton Mifflin Harcourt, April 30, 2013).
Mary Hickey adapted these bars from The Silver Palate Cookbook when she was a senior editor at Parents magazine, and everyone at her office fell in love with them. She and Sally Lee, Parents’ editor in chief at the time, secured their spots as true heroes by publishing “A Day in the Life of Liam: Pediatric Cancer Patient,” a photo essay, when it seemed no one else wanted to talk about pediatric cancer. —Gretchen Holt-Witt
Preheat the oven to 350?F. Line a 9 x 13-inch baking pan with foil.
Place the butter, sugar, and salt in a mixer bowl and beat until smooth and creamy, about 3 minutes. Add the egg yolk and vanilla and beat to combine. With the mixer on low, add the flour and mix to blend well. Scrape down the sides of the bowl and mix again. Press the dough into the bottom of the prepared pan. Transfer to the oven and bake until set and the edges are golden, 25 to 30 minutes.
Remove the pan from the oven, cover the crust layer with the chocolate chips, and return to the oven for 4 minutes. Remove the pan from the oven and spread the melted chocolate evenly with a spatula. Sprinkle with the nuts. Cool in the pan on a wire rack. When cool, remove from the pan and cut in 64 pieces.
Store in an airtight container for up to 3 days, or freeze for up to 3 months.