Preheat oven to 350°F (175°C). Line a half sheet pan with parchment paper or a silicone liner.
Whisk together the flour, baking soda, and salt. Set aside.
In a large bowl, combine the cooled butter, sugar, brown sugar, and vanilla until thoroughly combined.
Gradually add the flour mixture to the butter mixture in a few portions, mixing just until combined or a few streaks of flour remain.
Stir in the chocolate chips and nuts.
Transfer the dough to the prepared pan. Press into a rectangle roughly 9" x 13" and 1/2-inch thick, leaving about a 1 & 1/2-inch border around the outside.
Bake 16-20 minutes, or until the top is dark golden brown and firm.
Cool in the pan on a wire rack for 10 minutes. Then transfer to a wire rack. If it should break, that's fine.
After cooling completely, break the cookie brittle into 4- or 5-inch pieces.
Video
Notes
Store in an airtight container at room temperature up to 5 days.