From ArborWiki

(Singular: paczek, but nobody ever says that.) Traditional Polish pastries, associated with using up all of the good ingredients in the house before Lent. In the past couple decades, Paczki Day has spread out from Hamtramck to become a tradition in the Detroit area and now to Ann Arbor.

Like big jelly doughnuts -- but richer. Many grocey stores (e.g. Kroger, Meijer) sell large jelly doughnuts as paczki on Paczki Day, but they're posers. Real ones come from Hamtramck, Amadeus if you make prior arrangements, or Copernicus European Delicatessen. Dom Bakeries rates highly among stores not focused on Eastern Europe. There are probably other good sources too.

Dimo's Deli & Donuts are also known for their high-volume paczki selling, which are available filled with their standard donut fillings: custard, butter creme, apple, raspberry, blueberry and strawberry fillings.

[edit] For a field trip to Hamtramck

If you are going to Hamtramck for Paczki Day, some bakeries to stake out at 5am include:

• New Deluxe Polish Bakery, 11920 Conant (at Eldridge) (313)892-8165
• New Martha Washington Bakery, 10335 Joseph Campau, (313)872-1988
• New Palace Bakery, 9833 Joseph Campau, (313)875-1334
• Polish Market, Joseph Campau (at Belmont), (313)365-3731

[edit] Around the blogs

• Kitchen Chick discussion of Paczki Day, with a photo of Amadeus's paczki: http://www.kitchenchick.com/2005/02/paczki_day.html
• Kitchen Chick comes through again with an audio guide to pronounciation: http://www.kitchenchick.com/2008/02/paczki-day-tomo.html
• Chowhound has a 2007 thread on best Polish bakeries for paczki