Line a baking tray with silpat or parchment paper.
Roughly chop the pistachio. Keep aside.
Place the white chocolate in a large heat proof bowl. Place that bowl atop a saucepan of hot water. Keep stirring the chocolate till it melts. You can also melt chocolate in the microwave in 30 second increments.
Once melted, take the bowl off the heat and let the chocolate cool a bit for 3-4 minutes. Once its cooled off, gently stir in the rose water. If you add it while the chocolate is warm, your entire batch of chocolate will seize...this is experience talking!!
Now pour the chocolate rose mixture on to the prepared pan and spread it out evenly.
Sprinkle on all the toppings evenly all over the surface.
Transfer to the refrigerator for at least 2 hours to cool.
Once completely set, break into rough bite sized pieces. Enjoy!!