Salep, or ground orchid tubers. The roots are washed, boiled, dried, then ground into a flour used to thicken kaimáki ice cream, to give it a higher melting temperature.
Salep has been used since ancient times. The orchid roots—which resemble testicles, or orchis in ancient Greek (hence the English 'orchid')— were made into a popular hot drink in the Ottoman empire back in the days before coffee; the powder would be slowly added to simmering milk, with sugar, cinnamon and dried ginger. You can still buy in the centre of Athens.
Today wild orchids in Greece are protected, so the salep in the shops should come from cultivated orchids. Cheap versions replace the roots with corn flour.
Images by Lemur12, sahlep