In a bowl, with an electric mixer on medium speed, beat butter and brown sugar until well blended. Beat in eggs and vanilla until smooth, scraping down sides of bowl as needed.
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.
Drop dough in 2-tablespoon (1/8-cup) portions, 2 inches apart, onto buttered 12- by 15-inch baking sheets.
Bake in a 400° oven until cookies are lightly browned and no longer wet in the center (break one open to check), 6 to 8 minutes; if baking more than one pan at a time, switch pan positions halfway through baking.
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.
Note: Store these cookies airtight for up to 2 days.