Make the filling: chop white chocolate, place in a heatproof bowl, add pistachio paste. Melt and mix until combined and smooth.

Place the bowl in the fridge for 30 minutes, then scoop about 1 teaspoon each time and shape a bowl. place on a plate and freeze while making the dough.

Make the cookie dough: In a large bowl, beat butter, pistachio paste, brown sugar and white sugar. Beat until creamy, about 2 minutes. Add egg, vanilla extract and beat until combined, scrape the bottom and sides as needed.

Sift in flour, baking soda, salt. Mix until combined.

At this stage if dough is too soft, cover and refrigerate for 20 minutes.

Preheat oven to 350°F (175°C). line two baking trays with parchment paper.

Scoop out about 1-2 tablespoons of cookie dough and flatten it, place frozen pistachio filling in the center, roll into a ball.

Place rolled balls on a parchment paper with about 2 inches apart. Top each cookie with chopped pistachios (optional).

Bake for 10-12 minutes or until lightly browned on the sides.

Cool on baking sheets for 10 minutes before transferring to wire racks to cool completely.