Older Thais wouldn't blame you for thinking this dessert, featuring little green noodles in coconut milk with shaved ice, was from Singapore, as the name suggests. After all, it does look quite similar to cendol, a similar dessert found in Singapore, Malaysia and Indonesia.
They have their own version of the story. According to them, the dessert was once unique to a shop in Yaowarat, a district in Bangkok now also known as Chinatown. This shop used lod chong, short green noodles made of tapioca flour, water and pandan juice, and served them with coconut milk and jasmine-infused palm sugar syrup, garnished with chopped jackfruit and young coconut jelly. All this would be poured over shaved ice.
The stall had no obvious name, but it was in a distinctive location - it was in front of a cinema called Singapore Theatre. At first, people called it 'the lod chong shop at Singapore Theatre', but after a while, it was simply known as 'lod chong Singapore'.
The cinema closed but the name stuck. Many now assume it comes from Singapore, even earning the city-state its Thai nickname 'land of lod chong'.
Similar desserts of green noodles in sweet coconut milk or syrup, such as lod chong nam ka ti are commonly seen around the country. However, the variety of lod chong used in these desserts is usually made with rice flour rather than tapioca flour. This leads to a second theory that the name of this dish helped distinguish it from the regular rice version, as Thailand used to import most of its tapioca from Singapore.
Today, a dessert shop called Singapore Pochana stands in the fabled location, at 680-682 Charoenkrung Road.