Preheat your oven to 350°F (175°C) and line a 9x9 inch baking pan with parchment paper.

In a mixing bowl, blend together your chocolate brownie mix, eggs, and melted butter until just combined.

Pour the mixture into the prepared pan, smoothing the top with a spatula, and bake for 25-30 minutes, or until a toothpick comes out with moist crumbs.

Let the brownies cool completely in the pan on a wire rack.

Once the brownie base has cooled completely, carefully lift it from the pan using the parchment paper.

Cut the brownies into bite-sized squares and use your hands to roll each square into a ball.

Create a small hole in the center of each brownie ball and fill it with a dollop of rich pistachio cream.

Gently reform the brownie balls to ensure the cream is encased inside.

In a double boiler, melt your choice of dark chocolate over low heat, stirring until smooth and glossy.

Dip each filled brownie ball into the melted chocolate, ensuring they're fully coated.

Use a fork to lift them out, allowing excess chocolate to drip off, then place the coated brownie truffles on a parchment-lined tray to set.

While the chocolate coating is still wet, roll each truffle in the crushed pistachio nuts.

Once rolled, place the truffles back on the parchment-lined tray for the chocolate to set completely.

Refrigerate the chocolate-coated brownie truffles for about 30 minutes, or until the chocolate is firm and set.