In a mixing bowl, cream together softened unsalted butter and granulated sugar using an electric mixer on medium speed until light and fluffy, about 2–3 minutes.

Blend in instant espresso powder and vanilla extract until fully incorporated.

Gradually add all-purpose flour, mixing gently until the dough just comes together.

Fold in chocolate-covered toffee pieces, ensuring they are evenly distributed.

Wrap the dough in parchment paper, shape it into a log or disc, and refrigerate for at least 2 hours.

Preheat oven to 350°F (175°C), slice the chilled dough into rounds, and place them on a parchment-lined baking sheet.

Bake for 18–20 minutes until the edges are golden brown.

Let the cookies cool on the baking sheet for about 5 minutes before transferring to a wire rack to cool completely.