Melt high-quality chocolate and butter in a heatproof bowl set over simmering water, stirring until smooth. Remove from heat and mix in sugar until dissolved. Beat in eggs one at a time, followed by flour and cocoa powder, mixing until just combined.

Preheat oven to 350°F (175°C) and line a baking tray with parchment paper. Pour brownie batter into the prepared tray and spread evenly. Bake for 20 to 25 minutes until edges are firm but center is fudgy.

Allow brownies to cool in the tray for about 10 minutes, then transfer to a wire rack to cool completely.

Prepare the pistachio cream. Dip each brownie into the cream, ensuring they are well-coated.

Roll each brownie in chopped pistachios, pressing gently to adhere.

Place the coated brownies in the refrigerator for about 30 minutes to set.