Pandanus water (aka kewra water) is a flavor/essence extracted from the screwpine flower (not a pine). This is available as a fragrant, clear liquid usually in a clear glass bottle. Most stores that carry Indian and Middle Eastern groceries (particularly those dedicated to it) will have it. Alternatively, it is available online. The brands I prefer: Ahmed, Dabur, Laxmi. Keep all utensils cold until ready to use. Do not decorate the unbaked cookie with pistachio slivers as these tend to burn easily during the baking process. Cool the cookies completely before decorating with white chocolate. The gold dust is very delicate and scatters easily. Work quickly and with care in a draftless space. A dusting with gold stars, gold candy ‘pearls’ or gold ‘sugar’ is an acceptable alternative. Another alternate to decorating: In a small shaker jar, mix finely crushed pistachio with edible gold ‘stars’ and sprinkle generously over the chocolate doused cookie. Add the saffron threads before the chocolate hardens.