I spotted this fully prepared at a local Vietnamese supermarket, and on a whim decided to try it.
The chief ingredient is cassava, a.k.a. yuca (Vietnamese khoai mì), which gives it a starchy, mashed-potato-like texture; indeed, like a potato, it is also a tuber. But coconut, coconut milk, and sugar make the dessert sweet and give it most of its flavor, along with the ground sesame seeds topping it.
I’m not sure whether I was supposed to eat it cold, but I did. It was a little dry, but tasty. It tasted very much like rice pudding, but obviously without the same texture or moisture.
I do not know Vietnamese, but I believe the name of this loosely translates to “cassava cotton.” (Someone please correct me if I’m mistaken.)