Preheat oven to 180C.
Butter the sides of a 20cm x 20cm baking dish. Dust the sides with flour, and tap out excess. Line the bottom with parchment paper.
Remove cardamom seeds from their pods. Discard pods. Crush seeds in a pestle and mortar. If you don’t have a pestle and mortar, wrap the seeds in a newspaper and crush with a rolling pin (or the base of your frying pan). The seeds should not be crushed to a dust. The result should look like freshly cracked pepper. Set aside.
Melt chocolate and butter in a heatproof bowl set over a pan of simmering water, and gently stir. Take off the heat and add white and brown sugar, espresso and cardamom powder and stir to combine. Set aside and allow to completely cool.
Add eggs to chocolate mixture and stir to combine. Add flour and mix until smooth.
Pour the batter into the prepared pan and spread evenly. While baking, crush pistachios in a pestle and mortar. If you don’t have a pestle and mortar, wrap the pistachios in a newspaper and crush with a rolling pin (or the base of your frying pan).
Bake for 25-30 minutes, or until a toothpick inserted in the middle comes out with moist crumbs. Cool in the pan on a rack, then use the parchment paper to lift out the brownies before slicing into squares.
Adorn with pistachio dust, rose petals and a dusting of cocoa powder.
