Preheat oven to 375 degrees F (190 degrees C) with rack in center of oven. Line two baking sheets with parchment paper. In the bowl of your electric mixer (or with a hand mixer), beat the butter until smooth and creamy. Add the white and brown sugars and beat until fluffy (about 2 minutes). Beat in eggs, one at a time. Add the vanilla and beat until incorporated. Scrape down the sides of the bowl as needed. In a separate bowl, combine flour, baking soda, and salt. Add the dry ingredients to the egg mixture and beat until incorporated, adding the chocolate chips and nuts (if using) about half way through mixing. If you find the dough very soft, cover and refrigerate until firm (from 30 minutes to two hours). Makes about 4 dozen - 3 inch round cookies.
