Preheat the oven to 345 degrees F.

In bowl of a stand mixer, beat the cool butter until it is creamy. Beat in the sugar and brown sugar and cream for about 2 minutes. Reduce speed to low and add the vanilla and the eggs and beat just until eggs are incorporated, being careful not to beat a lot of air into the batter. I did this partially with the paddle and partially with my spatula scraper.

With mixer still on low, add the salt and the baking soda and scrape bowl. Add the baking powder and stir until it’s mixed in, then add the flour gradually until it’s incorporated, being careful not to over beat. Stir in the chocolate and the walnuts.

Scoop the batter into raggedy balls using a quarter cup size measure. Make sure they’re rough and not smooth. To be safe, you can gently shape large balls, pull them in half, then put the raggedy split sides up (and old trick from Cooks Illustrated). Put them on a plate in the refrigerator to chill for a few hours.

Bake the dough. Preheat the oven to 345 degrees F.

Arrange 8 dough balls on a parchment lined cookie sheet and bake for 15 minutes or until cookies appear set. Let them cool for 5 minutes on cookie sheet then transfer to a wire rack.