Just like in real life, pandas in Minecraft love eating cake! Just kidding, real-life pandas probably don't eat cake, and even if they did it would probably be something lame like bamboo cake.
But now, armed with this new knowledge, we can safely say that Minecraft pandas are on a different level of cute that surpasses that of real-life pandas (if that's even possible). A recent post on the Minecraft subreddit shows cold hard evidence of this fact,
We're not sure how this little detail slipped by unbeknownst to Minecraft players, or at least a good deal of them judging by this subreddit, for so long. Just look at the cuteness that we've been missing out on!
To be fair, pandas are rare mobs anyway, so you would have to find one first before you could see it eat the cake, wouldn't you?
Pandas only reside in jungle areas, so that's where you'll need to hang out. You might even be lucky enough to catch sight of a brown panda variant which is even rarer, or better yet, a baby panda! Those are the best, especially because there is apparently a 0.01666% chance per game tick that they will sneeze and drop a slime ball, causing all adult pandas within 10 blocks of the sneezing baby panda to jump.
Pandas apparently only spawn as babies 5% of the time, though, so it may take some time.
Anyway, back to the cake thing. In case you didn't know, you can craft a cake yourself by combining three Milk, two Sugar, one Egg, and three Wheat in the crafting grid. Just like in real life! Again, just kidding, you need at least four Wheats to craft a cake in real life.
Then, wielding your cake, you can approach your panda and drop the cake. If the cake is dropped close enough to it, the creature will scuttle up to the thing and start chowing down. And you'll start weeping from the cuteness.
Source: Reddit, Minecraft Wiki