The Oak Park Bakery is justifiably proud of their butter coffee cakes. Today and tomorrow (July 15 & 16) they're having a pre-vacation sale: buy one at the regular price and get a second a half price. Since the coffee cakes are mostly priced in the $5-6 range, this is quite a bargain.
They're famous for their fresh strawberry, but the other flavors are great too. I can personally speak to the cheese, blueberry cheese, pecan, prune, and raspberry. But note that by 9 a.m. this morning they were already out of cheese and raspberry!
Oak Park Bakery
904 South Oak Park Ave
Oak Park.
(Not sure of the hours but they open very early--before 7 I think).