1. In a bowl, with an electric mixer on medium speed, beat butter, brown sugar, granulated sugar, and vanilla until well blended and smooth; scraping down sides of bowl as needed.
2. In another bowl, mix flour, baking soda, and salt. Stir or beat into butter mixture until well incorporated. Stir in chocolate chips and pecans, if using.
3. Dough will be crumbly; pinch into 1-tablespoon lumps and drop about 2 inches apart, onto buttered 12- by 15-inch baking sheets.
4. Bake in a 300° oven until cookies are an even golden brown, 18 to 20 minutes; if baking more than one pan at a time, switch pan positions halfway through baking.
5. With a wide spatula, transfer cookies to racks to cool. If hot cookies start to break, slide a thin spatula under them to release; let stand on pan to firm up, 2 to 5 minutes, then transfer to racks to cool completely.
Note: Nutritional analysis is per cookie.