With over 150k of these bagel-like pretzel-like circular things eaten daily, the obwarzanek is one of Krakow's staple street foods. You'll find stands all over the city and they are also available in most bakeries. Like pretzels in other cities they are a nice quick bite to fill your stomach while strolling around the city.
There are different varieties but the most common ones are available with sesame, plain, poppy seed or cheese. Some restaurants will also offer them toasted with different spreads. They are originally from Krakow and its worth having the original during your stay.
The set of toasted obwarzanki with butters or dips at Bunkier Sztuki are recommended.