Step 1: Preheat the Oven and Prepare the Baking Sheet
Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.
Step 2: Mix Dry Ingredients for Cookies
Whisk together flour, cocoa powder, baking soda, and salt in a bowl.
Step 3: Cream Butter and Sugars
Beat butter, granulated sugar, and brown sugar until smooth and fluffy.
Step 4: Add Wet Ingredients
Add egg and vanilla extract. Mix until combined.
Step 5: Combine Wet and Dry Ingredients
Gradually add dry ingredients into the wet mixture, stirring until just combined.
Step 6: Stir in Dark Chocolate Chips
Fold in the dark chocolate chips, making sure they're evenly distributed.
Step 7: Shape the Dough
Drop rounded spoonfuls of dough onto the prepared baking sheet, spacing them about 2 inches apart.
Step 8: Bake
Bake for 10-12 minutes, until edges are firm. Cool on the baking sheet.
Step 9: Make Espresso Frosting
In a small saucepan, dissolve espresso powder in heavy cream over low heat. Remove from heat.
Whisk in softened butter and powdered sugar until smooth and creamy.
Step 10: Frost the Cookies
Once the cookies have cooled, spread the espresso frosting on top of each one.