Dissolve 1 tablespoon of instant coffee in 2 tablespoons of hot water and let cool slightly.

Beat together 1 stick of softened unsalted butter and 1 cup of icing sugar until light and fluffy (3-4 minutes).

Incorporate 1 large beaten egg into the mixture, then fold in the cooled coffee mixture.

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

Gradually fold the dry ingredients into the wet mixture until just mixed.

Transfer the dough into a piping bag and pipe small dollops onto a lined baking tray.

Chill the piped cookies in the freezer for 5-10 minutes.

Preheat the oven to 350°F (175°C) and bake for about 8 minutes until lightly golden.

Dip cooled cookies in melted dark chocolate and sprinkle with chopped pistachios.