Dry roast the pistachio till just before they have browned and take them off the heat and transfer them to another container.
Once cool, chop the pistachios into small pieces. Chop the cranberries into smaller pieces too
Keep everything ready in separate bowls.
Place parchment paper on a baking tray or any large plate and keep it ready.
Chop the white chocolate into small pieces.
Take the white chocolate in a microwave-proof glass container with a wide mouth.
Melt in the microwave in bursts of 20 seconds, 20 seconds and then 10 seconds.
Each time, stir it a little bit. Towards the end, you can do it for another 10 seconds and whisk for a couple of minutes to bring the temperature down.
Pour the white chocolate into the prepared tray. Spread with a spatula to a moderately thin layer.
Sprinkle pistachio, cranberries and rose petals all over and gently press them a little.
Let this cool down and solidify. If it is not too hot where you live, then this will become solid within no time. Or else, you can transfer the tray to the refrigerator for 10 to 15 minutes and it will set.
Once set, break this into as many pieces as you want.
Store in an airtight container in the refrigerator for a month. If you are keeping outside and if you have a favourable climate, then this will stay good in a cool place as well.