Brown the butter. Heat it in a small pan over medium heat. Don’t walk away! It will bubble and foam up a bit, and then the bits on the bottom will start to turn brown. Stir it every so often to keep it from burning. Once the bits on the bottom are a nice amber-ish color, take the pan off the heat and pour the butter into a large mixing bowl.
In a large mixing bowl, use a wooden spoon or spatula to mix the butter, sugars, vanilla, and maple extract until well combined. Add eggs one at a time, mixing after each addition.
Add half of the flour, all the baking soda, espresso powder, and kosher salt. Mix, then add the rest of the flour. You will think there is too much flour. There isn’t. Keep mixing. Once the flour is incorporated, mix in the chocolate and pistachios. Check the dough--it shouldn't feel wet, but it shouldn't feel dry, either. If it seems a little dry, add a splash of milk until it feels right.
Cover and chill for one hour. Don’t skip this step!
When ready to bake, preheat oven to 350 degrees F. Scoop dough into 1/3 cup mounds and place onto an ungreased baking sheet. Be sure to leave space between the cookies—these are big, so I only do 4-5 per baking sheet. Bake for 15-16 minutes or until starting to turn darker around the edges. Remove from oven, sprinkle generously with sea salt, and cool on baking sheet for ten minutes before moving them to a wire rack. Serve warm!
