1 First brown the butter. Melt the butter in a medium sized, thick-bottomed, stainless steel saucepan (use stainless steel so you can tell when the butter has browned) on medium heat. Continue to cook while the butter goes through various stages of bubbling up and releasing its moisture. Whisk frequently over several minutes. When you start to smell the nutty aroma of the butter browning, and you can whisk aside some of the foam to see small browned bits at the bottom of the pan, remove from heat and pour off into a bowl. Do not dawdle at this point as it is easy for the butter to go from browned to burnt.
2 Place the flour, salt, baking soda, and cinnamon in a bowl and vigorously whisk together.
3 Preheat oven to 350°F. Pour browned butter into the bowl of a stand-up mixer (if you don’t have a mixer, you can just beat by hand). Add the sugars and beat until smooth. Add the eggs, beating after each addition. Add the vanilla extract and beat for 3 more minutes.
4 Stir the flour mixture into the butter sugar mixture a third at a time. Stir in the chocolate chunks and the nuts (if using). Up to this point you can make ahead a day or two and store the cookie dough in the refrigerator until ready to cook.
5 Line cookie sheets with Silpat or parchment paper (or just lightly butter rimmed cookie sheets. Spoon out heaping tablespoon hunks of batter onto the cookie sheets, separated by at least 2 inches, allowing room for the cookies to spread as they cook. You may need to work in batches.
6 Cook at 350°F for about 12 minutes, the edges of the cookies should be just a little browned. Remove from the oven, let cool on the cookie sheet for 5 minutes. Then remove the cookies to cool completely on a rack.