What's an acceptable substitute for Pandan Leaves?
If you have an indian market nearby, you can get kewra extract/essence.  Kewra is the indian name for pandanus plant and kewra essence is featured in a number of indian desserts.  I don't recall seeing kewra leaves in my local indian market, but I use kewra essence regularly.  (Careful, sometimes it's sold as a very concentrated oil extract and sometimes as the more dilute kewra water; so how much you need to add will depend on which form of kewra you buy).

Not too long ago, I made a Thai custard (usually served with sticky rice) that called for pandanus extract.  It was researching where to purchase that when I discovered that I already had it in my cupboard.  Great stuff.