Prepare the Coffee Mixture: In a small bowl, combine the instant coffee or espresso powder with a small amount of the vanilla and egg mixture. Stir until the coffee dissolves and set aside.
Cream the Butter and Sugar: Add the softened butter and granulated sugar to a large mixing bowl. Beat until smooth, creamy, and slightly fluffy.
Add the Egg and Vanilla: Beat in the egg and vanilla extract until the mixture is smooth and well combined.
Add the Coffee: Pour in the prepared coffee mixture. Mix until the coffee is evenly incorporated and the dough has a rich coffee aroma.
Combine the Dry Ingredients: In a separate bowl, whisk together the all-purpose flour, baking powder, and salt.
Make the Cookie Dough: Gradually add the dry ingredients to the butter mixture. Mix just until a soft dough forms. Avoid overmixing to keep the cookies tender.
Shape the Cookies: Scoop the dough into small portions and roll each portion into a ball. Place the dough balls on parchment-lined baking sheets, leaving space between them.
Create the Fork Pattern: Gently press each dough ball with the back of a fork to slightly flatten the cookies and create classic ridges.
Bake the Cookies: Preheat the oven to 350°F (175°C). Bake for 10–12 minutes, or until the edges are lightly golden and the centers look set.
Cool the Cookies: Let the cookies cool on the baking sheet for a few minutes. Then transfer them to a wire rack and allow them to cool completely.
Serve and Enjoy: Serve the coffee butter cookies once cooled. Enjoy them with freshly brewed coffee, espresso, tea, or your favorite warm beverage.