Preheat oven to 350° F. Line a cookie sheet with parchment paper, or spray the sheet with cooking spray.
Toast the chopped pecans for about 5 minutes in a 350 ℉ oven or toaster oven, or until aromatic and just beginning to brown. Remove from oven and cool to room temp. (Be sure to keep an eye on them. It’s so easy to burn pecans when you only meant toast them!)
Meanwhile, cream butter and brown sugar together in the standing mixer or with a hand-held beater. Beat in egg until well incorporated. Stir in vanilla and espresso.
Add dries (cream of tartar, baking soda, salt and flour) and mix until thoroughly incorporated. Stir in chocolate chips and pecans.
Refrigerate cookie dough for 20-30 minutes before baking. You can also refrigerate it overnight or for several days before baking.
Drop by rounded spoonful onto prepared cookie sheet.
Bake for 10-12 minutes, or until they look how you like your cookies to look! 🍪