First, whisk together the brown sugar, white sugar, and melted butter in a bowl until combined.
1 cup brown sugar, ¼ cup white sugar, ¾ cup melted butter
Then add the egg, egg yolk, and vanilla extract. Whisk until combined.
1 egg, 1 egg yolk, 2 teaspoons vanilla extract
In a separate bowl, whisk together the flour, espresso powder, baking soda, and salt. Then slowly add the flour mixture to the wet ingredients. Whisk until just combined.
2 cups all-purpose flour, ¼ cup espresso powder, ¾ teaspoon baking soda, ¾ teaspoon salt
Now gently fold in the chocolate chips. Let the espresso cookie dough rest in your refrigerator for at least 30 minutes and up to 24 hours.
1 ¼ cup chocolate chips or chopped chocolate
Preheat your oven to 350 °F (180 °C).
Next, roll the dough into balls or use a cookie scoop to scoop the dough onto your baking sheet lined with parchment paper. Bake for around 12 minutes until the edges just start to brown.
Let the cookies rest for a few minutes and enjoy!