Step 1: Preheat and Prepare
Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper.
Step 2: Mix Dry Ingredients
In a bowl, whisk together the flour, baking soda, and salt. Set aside.
Step 3: Cream Butter and Sugars
Beat the softened butter with the granulated and brown sugars until fluffy and light.
Step 4: Add Wet Ingredients
Add the egg and vanilla extract. Mix until fully incorporated.
Step 5: Combine Dry and Wet Ingredients
Gradually add the dry ingredients to the wet mixture, stirring until combined.
Step 6: Fold in Chocolate Chips
Fold in the chocolate chips, ensuring they are evenly distributed.
Step 7: Make Espresso Marbling
Dissolve the espresso powder in hot water, creating a smooth espresso paste.
Step 8: Form the Cookies
Scoop dough onto the baking sheet. Drizzle the espresso paste over the dough, then gently swirl with a toothpick.
Step 9: Bake
Bake the cookies for 12-15 minutes, or until the edges are golden and crispy.
Step 10: Cool and Serve
Let the cookies cool on the baking sheet before transferring them to a wire rack.