It's all the things that quick and easy snack food should be - filling, tasty and a bit messy.
Basically it's a long flat toasted roll, hand-prepared with a topping of cheese and fresh mushrooms laced with tomato sauce.
Some zapiekanki (the plural form) are huge, they're always cheap (about $1.50), and they're ideal for warming you up quickly on a chilly day.
You can buy the zapiekanka all over Poland, usually from informal street stalls.
On top of the basics, any number of other ingredients may be added: garlic sauce, ham, salami, corn, etc.
Some zapiekanki stalls go a bit crazy in the variety they offer - check out the bewildering array of options on the menu below :
As with all fast food, quality varies; once you find a place that serves a great zapiekanka, however, you'll never go anywhere else.
If you're visiting Toruń, look for its window on the corner of ul Różana and ul Ducha Świętego.
Another top zapiekanka outlet I encountered was housed within this circular building in Plac Nowy, Kazimierz, a neighbourhood in beautiful southern Kraków:
I'm due to go back to Poland soon, for the first time in three years. I hope those zapiekanka stalls have survived. If so, smacznego!*