Always measure your flour with care, ideally by weight, to avoid excess which can alter the texture. Chilling the dough enhances flavor and limits spreading, yielding a thicker, chewier result. For added richness, fold in 1/2 to 1 cup of toasted chopped walnuts if desired. Cookies are perfectly baked when the edges are lightly browned but the centers still appear slightly underbaked—they will firm up as they cool.