Method:
Preheat oven to 350°F. In a large mixing bowl, cream the butter, peanut butter, sugar, brown sugar, egg and vanilla extract. Whisk together the flour, baking soda and baking powder and add to peanut butter mixture, stirring to combine well. Stir in chopped peanuts and chocolate chips.
Drop generous spoonfuls of dough onto an ungreased cookie sheet. Press each mound of dough with a fork to flatten slightly.
Bake until bottom of cookies are golden brown, about 10 minutes. Remove from oven and sprinkle immediately with fleur de sel to taste. Let cookies cool on sheet for a few minutes before transferring to a cooling rack to cool completely.