(a little pink food colouring added to the meringue mixture will give you a nice dusty pink colour if you so wish)
Preheat oven temperature to 110 C. Line a baking tray with baking paper.
Place the egg whites in a large bowl and whisk until foaming. Carefully pour the sugar slowly into the egg whites. Once it has all been added, add the rosewater and continue to whisk until the mixture is very thick and holding its shape. If using the pink food colouring you can add this at this stage.
Place the chopped pistachios onto a plate and using 2 large spoons scoop a dollop of meringue mixture between the two and roll in the pistachio nuts.
Place on the baking tray, placing them well apart. Cook in the oven for 2 hours.
Remove from the oven and allow to cool. The meringues will keep nicely in a dry, sealed storage container for quite a few days.