sweetened condensed milk
Thickened, heavily sweetened milk, syrupy and caramel-sweet.
Sweetened condensed milk is sold in cans or tubes in most larger supermarkets, and reliably in Asian and Turkish grocers. It should not be confused with unsweetened evaporated milk, which often sits next to it on the shelf.
Substitute:
Unsweetened evaporated milk is not a substitute, because it lacks both the sweetness and the thickness. In a pinch it can be simmered slowly with roughly its own weight in sugar until syrupy.