In a stand mixer, cream together butter, granulated sugar and brown sugar at medium high speed until smooth and creamy and butter is lighter in color, about 2-3 minutes. Beat in the eggs, one at a time, and vanilla extract.
*Option 1 - for strong, bold coffee flavor, dissolve 2 tablespoons of espresso powder into 2 tablespoons of water. Mix dissolved espresso into the butter-sugar mixture.**Option 2 - for more subtle coffee flavor, add just 2 teaspoons of dry (undissolved) espresso powder to the flour mixture (skip to the next step). In a medium bowl, combine flour, baking soda, and salt. **For more subtle coffee flavor, add the desired amount of espresso powder to the flour mixture (do not dissolve in water). Reduce the mixer speed to low. Gradually beat in flour mixture. Fold in the espresso/chocolate chips.
Refrigerate the dough a minimum of 30 minutes before shaping. When you're ready to shape dough, preheat the oven to 350℉. Spoon about 2 tablespoons of dough onto a baking sheet, spacing 2 inches apart. Repeat until the cookie sheet is full.
Bake cookies for 10 to 12 minutes, until lightly golden but still soft. Allow cookies to cool partially on the baking sheet for 5 minutes before transferring to a cooling rack or wax paper to finish cooling.