Originally from Cooky Cat: Our beloved David D. Wronski (aka "The Polish Prince") definitively writes . . .
As you already know from the previous writing on the subject, pączki("poonch-kee") are Polish style jelly donuts available the year around from any self respecting Polish bakery. Be advised, though, pączki are to jelly donuts what Ferraris are to Ford Pintos. Or, pink Champagne is to Cold Duck. We do not exaggerate!
FYI, there are two styles. The version with the jelly in the dough wrapping before deep frying (rare); and, the kind with the jelly added in after the dough is deep fried (usual). Being a decent Polish lad at heart (of Polish descent) my life has being in part a search for the perfect jelly donut. The Polonia Bakery in Passaic, New Jersey arguably has the very finest this boy has ever had. They make the first type (jelly fried-in) and are the nicest folks. Here is a link to an excellent review in Edible New Jersey magazine. Below are my on site photos (date: February 4, 2016) from Piast in Garfield, New Jersey where we also shop. They had Marmalade, Rose jelly, and Bavarian Cream. Rather too little filling for my taste. And, it was quite a go around getting a bead on what exactly was "Marmalade". They sell jars of a Marmalade, so I figure they just took the name from there. Turns out it's mixed fruit jam. Afterward we went to Polonia and got some more, filled with prune butter/lekvar (in Polish it's "Povidla", pronounced "Povidwa"). As I said, Polonia is the definitive version. Jelly fried-in, orange zest flecked thin glaze icing. Light, flavorful, delectable.
And, let's just touch on the subject of the amount of jelly. This pertains to the style with the jelly squirted/slipped in after it's a donut. You want those babies to be a little heavy with the filling. Jelly in every bite is the action standard. When I worked in my Polish Uncle's bakery on Friday's preparing for the big Saturday sales day, my last job after having worked 12 or so hours overnight was to fill the pączki. That was probably what got me through the night, the anticipation of being left alone to fill those little treats at my very own sole discretion. And, fill them I did. Heavy hand on the jelly dispensing machine. Like the one shown below.
Also, freshness is key. Best to get your pączki (that's plural, singular is pączek) as close as possible to having been made. (Not you — having been made — but, the pączki, silly) Not to belabor the "having been made" double entendre, but close to having been made with jelly donuts is the same as the other meaning: make that, in the morning. There seems to be a 4 hour or so window of opportunity. After that they start to become contenders for a game of hockey.
Getting back . . . But there is a single day, little known, the zenith day for pączki. It comes just before Ash Wednesday, the beginning of Lent, officially celebrated on Fat Thursday, the Thursday before Fat Tuesday (Mardi Gras). On Pączki Day, to meet demand, the number of pączki made for sale jumps 10X . I suggest you call ahead and place an order. Recommended varieties: apricot and raspberry jam, rose (the flower) jam, and Bavarian cream. But, do not leave without mass quantities filled with Powidła (prune butter)---the ne plus ultra (pronounced "po-veed-wa".) [A diagonal mark across the letter L, written as "ł" in the Polish language, is pronounced "wa". And, just so you are thoroughly aware of the upside down nature of the Polish mind — one of which I happen to have . . . so I can comment . . . — the letter W is pronounced as an English "V". Go figure.]
If you want to get in on the festivities, do check with your local Polish baker to find out on what day they will be honoring that fabulous fabled fried fritter; probably Fat Thursday [It took me several years to get it straight about which day was Pączki Day. I would typically saunter in on Fat Tuesday and receive a wilting look from the lovely sales girl at the bakery. In fact, I dearly remember Pączki Day from my youth; but it wasn't until my wizzoned adult years that I finally figured out on what day it fell and its significance. Thank you, Google. Thank you, Internet. Thank you jelly. Thank you, Alanis Morissette---Thank U.]
For a truly beatific experience, while you are buying your pączki, also ask for chruściki ("krus-chee-kee"), another traditional favorite at this time of year. Chruściki---when they are made right---are as light and tender as angels' wings. In fact, translated, chruściki means "angel wings." As my mother would say, "Be an angel, pass the chruściki." But watch out for all that powdered sugar; it's a real game changer if you are wearing your favorite black slacks or that little black dress. They can be little devils plenty if you don't partake with precision and perspicacity. [I honor the letter "P", for pączki; get it? Really, get some.]
Additionally... I have also suggested that Voodoo Doughnuts be ready for the action. When in Portland, look them up. Find out for yourself what they are talking about when they say "the magic is in the hole."