Preheat your oven to 350°F (175°C) and prepare a 9x9-inch baking dish lined with parchment paper.

Melt dark chocolate and butter together in a heatproof bowl over simmering water, stirring continuously until smooth.

In a mixing bowl, whisk the eggs and sugar together until pale and frothy, for about 3-4 minutes.

Gently fold the melted chocolate mixture into the egg-sugar blend until smooth.

Sift the flour into the chocolate-egg mixture and fold gently until just combined.

Pour half of the brownie batter into the prepared baking dish and dollop pistachio cream evenly over it.

Spread the remaining brownie batter over the pistachio cream layer, smoothing the top.

Bake for 25-30 minutes until a toothpick inserted comes out with a few moist crumbs.

Allow the brownies to cool completely in the baking dish for about an hour, then cut into squares and coat with crushed pistachios.

Serve at room temperature with whipped cream or vanilla ice cream.