Dissolve 1 tablespoon of instant coffee in 2 tablespoons of hot water in a small bowl. Stir until completely dissolved, then allow the mixture to cool slightly.

In a mixing bowl, cream together 1 stick of softened unsalted butter and 1 cup of icing sugar using an electric mixer on medium speed for about 2-3 minutes.

Add one beaten large egg to the creamed butter and sugar mixture, mixing until fully incorporated.

In a separate bowl, whisk together 2 cups of all-purpose flour, 1 tablespoon of cornstarch, and 1 teaspoon of ground cinnamon until well combined.

Fold the cooled coffee mixture into the creamed batter, mixing gently. Gradually add the dry ingredients until the cookie dough is thick and slightly sticky.

Transfer the cookie dough into a piping bag fitted with a large star or round tip. Pipe small dollops onto a lined baking tray, spacing them about 2 inches apart.

Place the piped cookies in the freezer for 5-10 minutes to prevent spreading during baking.

Preheat your oven to 350°F (175°C). Bake the cookies for about 8 minutes, or until the edges are lightly golden.

Allow the cookies to cool on the tray before transferring to a wire rack. Once cool, dip the edges in melted dark chocolate and sprinkle with chopped pistachios.