A “breakup cake” is for couples breaking up, just as a wedding cake is for couples getting together in marriage. A breakup cake can contain a graphic display or just a simple message.
 
“Breakup cake” has been cited in print since at least 2000.
 
   
11 February 2000, Los Angeles (CA) Times, “Just in Time for the Holiday: a Magazine for the Ex-Generation” by Steve Harvey, pg. B3:
Southern California’s Divorce Magazine (yes, there is such a publication) reports that a recent divorce party included “a breakup cake” (like a wedding cake, but each side is entitled only to half).”
     
19 June 2002, Chicago (IL) Tribune, “Happy ending . . . to a marriage?” by Karla Zimmerman, sec. 8, pg. 2:
Dick’s Last Resort restaurant at 435 E. Illinois St. has offered a divorce party package for the past few years. It includes a “breakup cake” (a gender-appropriate, anatomically shaped sheet cake broken into pieces), new little black book, personal ad and T-shirt for the divorcee, in addition to food for the group.
 
Twitter
Victoria Walberg
‏@vickyjo
@cadavreexquis Wowee, imagine the blood sugar crash after that.  Sounds like breakup cake.  Like the sound of the cheesecake mmm ameretto
6:00 PM - 27 Jan 2009
   
YouTube
Cake Boss: Break Up Cake
LongShotProdLLC
Uploaded on Jul 13, 2011
Cake Boss
Season 4, Episode 18
“Bugs, Break Ups & Burned- Out”
Original Airdate: July 11, 2011
 
Twitter
♡Chris Liberty
‏@ifiancini
Cake 4 everything? °Wedding cake °Tradition wedding cake °Engaged cake °Courtship cake °Breakup cake °Divorce cake °Burial cake. #Lol
3:05 PM - 8 Mar 2014
 
Twitter
Abby Louise Lakey
‏@abbylakey
shout out to my single friends, me and @JemCockerill94 starting the ‘breakup cake’ business #staystrong #hollaforcake
6:25 PM - 30 Aug 2015
   
Eater
One Whole Foods Is Selling Breakup Cake
by Chris Fuhrmeister Feb 15, 2016, 5:34p @ccfuhr
(...)
A bakery employee at the Brookline Whole Foods told Eater the cake is meant to elicit a post-Valentine’s Day chuckle: “I think my manager said, ‘Let’s just make a few of these as a joke and then see what happens.’” In addition to the vanilla-frosted cake shown in the above photo, the employee confirmed there’s a chocolate version too. That cake features a large heart with “We need to talk” in the middle. Both cakes check in at $5.99.
 
Eater reached out to several other Whole Foods locations, and it appears the breakup cakes are available only at the Brookline store.
 
Red (UK)
Breakup Cakes Are A Thing Now
Megan Sutton By Megan Sutton Posted on February 18, 2016
After being broken up with, most of us to tend to head for the carbs, so really, the Eat Your Heart Out Project makes perfect sense.
 
Isabella Giancarlo, a Brooklyn-based designer has set up the online project, ‘taking words remembered from breakups and re-imagining them as something sweet.’