Preheat your oven to 350°F (175°C) and grease a 9x9-inch baking pan.
In a large mixing bowl, combine the melted butter and granulated sugar, whisking until smooth.
Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.
In a separate bowl, whisk together the flour, cocoa powder, baking powder, and salt.
Gradually add the dry ingredients to the wet mixture, stirring until just combined.
Gently fold in the chopped pistachios, chopped Ferrero Rocher chocolates, and chocolate chips.
Pour the brownie batter into the prepared baking pan, spreading it evenly.
Bake for 25-30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
Allow the brownies to cool in the pan for at least 15 minutes before cutting into squares.