This is Taiyaki currently.
Taiyaki (originally known as, "Fish Dung Cakes") is a piece of Confectionery that was invented by Bubble Bass, but stolen by Japan. They are waffle batter solidified in a fish shape and filled with beans, Chocolate and other stuff (formerly Bubble Bass's poop) and sometimes barth out a Wafer, Mochi and Ice Cream, and they have a long history.
History
In 1696 AD, after disliking his first visit to the Krusty Krab, Bubble Bass decided to make his own food so he dosen't suffer eating the food at The Krusty Krab. So he made Taiyaki, it was very different, it was shaped like Bubble Bass and made of his poop, nothing really changed over time.
But then, 3017 AD, Bikini Bottom is annihilated by bombs, 5 weeks later, Japan discovered a crate of Fish Dung Cakes, completely unaffected by the radiation, they toke it back to Nintendo's labs, they decided to keep the legacy going by claiming it as there own, renaming it to Taiyaki, making it look like a traditional fish and making the inside more appealing, and here we are now.