Step 1: Preheat and Prep
Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper.
Step 2: Mix Dry Ingredients
In a bowl, whisk together flour, baking soda, and salt.
Step 3: Cream Butter and Sugars
Beat butter, brown sugar, and granulated sugar until light and fluffy.
Step 4: Add Wet Ingredients
Add eggs and vanilla, mixing well. Gradually add dry ingredients and mix until combined.
Step 5: Prepare Espresso Swirl
Dissolve espresso powder in milk and mix it into a thick paste.
Step 6: Form the Cookies
Drop spoonfuls of dough onto the baking sheet, placing a small dollop of espresso paste in the center. Swirl gently with a toothpick.
Step 7: Bake
Bake for 10-12 minutes or until edges are golden. Let cool on a wire rack.