Joe Manganiello's birthday cakes tasted awfully familiar this year ... his girlfriend, Caitlin O'Connor, bought his sweet treats from a bakery often frequented by his ex-wife, Sofía Vergara.
Bakery sources tell TMZ ... Caitlin ordered 2 birthday cakes for Joe’s birthday from Cake and Art bakery in West Hollywood, Calif. ahead of his 48th name day ... which certainly raised eyebrows given Sofía's history with the hot spot.
We're told the cakes -- which came out to a whopping $400 total -- each had their own design and flavor.