3. Dissolve espresso powder in 1 teaspoon warm water in a custard cup.

4. To melt butter in the microwave, place the butter in a microwave-safe bowl and microwave (1100 watts) on HIGH for 35 seconds. This will melt almost all the butter with the center not completely melted. Stir the butter until completely melted. This will prevent the butter from being too hot when the eggs are added. You can also melt the butter in a saucepan on medium-low heat just until melted.

5. Combine butter and sugars in a large mixing bowl. I use a stand mixer. Beat at medium speed of an electric mixer until blended. Add egg, egg yolk, and dissolved espresso powder and beat just until combined.

6. Add flour mixture to the mixing bowl; beat just until flour is incorporated. Add chocolate chips and beat just until incorporated or stir them in by hand.

7. Spoon cookie dough onto a lightly greased baking sheet or a baking sheet lined with parchment paper. I like to use a very small ice cream scoop so I get the same amount of dough every time and it makes perfectly round scoops. Bake 9 to 10 minutes at 350°. The center will still be slightly doughy but the cookies will firm up when cooled. If you over bake these cookies, they will lose their soft, and chewy texture. Let cookies cool 2 minutes on the baking sheet then transfer to cooling racks to cool completely.

Notes

If you have trouble finding it or want to use what you have, just double the amount to 4 teaspoons and use instant coffee granules (not coffee grounds).
If you don’t have either espresso powder or instant coffee granules, you can use 2 teaspoons of extra strong brewed coffee, but it will not have as much coffee flavor. Do not use more brewed coffee than 2 teaspoons because it will affect the texture of the cookies.