Position a rack in the center of the oven. Preheat the oven to 375°F. Grease cookie sheets. Whisk together thoroughly:
      18 tablespoons all-purpose flour
      1/2 teaspoon baking soda
Beat on medium speed until very fluffy and well blended:
      8 tablespoons unsalted butter, softened
      1/2 cup sugar
      1/2 cup packed light brown sugar
Add and beat until well combined:
      1 large egg
      1/4 teaspoon salt
      1 1/2 teaspoons vanilla
Stir the flour mixture into the butter mixture until well blended and smooth. Stir in:
      1 cup semisweet chocolate chips
      3/4 cup chopped walnuts or pecans (optional)
Drop the dough by heaping measuring teaspoonfuls onto the sheets, spacing about 2 inches apart. Bake, 1 sheet at a time, until the cookies are just slightly colored on top and rimmed with brown at the edges, 8 to 10 minutes; rotate the sheet halfway through baking for even browning. Remove the sheet to a rack and let stand until the cookies firm slightly, about 2 minutes. Transfer the cookies to racks to cool.