Halawa Tahinia is made from tahini (sesame seed paste), combined with sugar, and shaped into blocks.
Traditionally, halawa was made in two varieties, a hard brittle type, and a less common chewy dough like variety. Both were sold in tins.
Nowadays, many additions and variations exist, such as halwa with pistachios, halwa with chocolate, halwa with hazelnuts, and more.
Halwa is eaten as a filling in sandwiches made from pita bread.
Because it is rich in calories and filling, and not expensive, it is a staple of the working class. It also need no fridge to keep for a long time.
A joke in Egypt goes: "we will bring you pita bread and halawa حنجيب عيش و حلاوة", which means that one may go to prison where visitors will bring bread and halawa.