Preheat oven to 325. Lightly spray 2 (or more) baking sheets with nonstick spray.
(I used parchment paper instead)
Beat the butter in an electric mixer on medium speed for 2 minutes.
Sift the powdered sugar into the mixer bowl, and continue to mix for 8-10 minutes. Mix in the vanilla extract.
In a medium bowl, mix the flour and coffee. Reduce speed to low and add to the mixer bowl. Beat only to incorporate, no more than 1 minute. It will be a dry, textured dough.
Scoop out 1 tablespoon portions, place on baking sheet and flatten slightly with your hand.
Bake for 15 - 20 minutes, until lightly golden. Set aside to cool 5 - 10 minutes.
Store in containers for up to a week.