Fionna and Cake is the 61st episode of Adventure Time and the 9th episode of season 3. It first aired on September 5, 2011.
In the gender-swapped world of Adventure Time, Fionna and Cake are at Prince Gumball's castle when Ice Queen attacks. After the attack, Gumball and Fionna try to get closer to one another and try to begin a Plot The episode starts off with Fionna and Cake inside Prince Gumball's castle helping him prepare for his Gumball Ball. But then Cake senses something and Fionna checks it out and goes to the castle's balcony. She sees many dark swirling clouds and Ice Queen comes out of them and attacks the castle. She sends a huge boulder of ice and blasts into the castle. Once she's in the castle she has a short battle with Fionna. She states that Fionna keeps all the babes to herself. She then forms a sludge beast with her Ice Powers and attacks Prince Gumball. Fionna then tells Cake to turn into morning star mode to smash the slush beast. When Fionna beat the slush beast the room then was filled with snow, Prince Gumball was left unharmed but Ice Queen mysteriously vanished. Prince Gumball says that Fionna looked beautiful and the snow and asked her out. Fionna then blushes and is confused, but Cake interrupted them and agreed with Prince Gumball. Then Prince Gumball says to them to meet him in the Castle Gardens in an hour.
In the Tree Fort, Fionna and Cake argued whether or not Prince Gumball asked Fionna on a date. Cake insists she joins Fionna and Prince Gumball, with her dulcimer. Fionna then agrees just to prove Prince Gumball didn't ask her on a date. In the Castle Gardens Prince Gumball is accompanied by Lord Monochromicorn. Prince Gumball gives Cake catnip Lord Monochromicorn picked for himself, and Fionna a bouquet of posies, inside is a retractable Crystal Sword. Fionna then says she is all about swords, then says "wow". Prince Gumball then says the wowiness has only just begun.
Then they take off. Cake tells to Fionna to Gumball that he's "hot". Fionna disagrees with the idea, and almost yelling Cake said, "Boys like to hear that they're hot!" Prince Gumball challenges Fionna a race to Marshmallowy Mweadows. Fionna then accepts the challenge and then Fionna and Gumball took off. After the race Prince Gumball jumps under a field of flowers. Fionna panicked and jumped too. Prince Gumball said he saw pearl pygmy skullum in there, which reminds him of Fionna the ways her eyes sparkle. The group then takes off to the sky, and Prince Gumball sang to Fionna , and Cake played along with her Dulcimer. The flight ends with Cake and Lord Monochromicorn leaving the two alone. Cake winks at Fionna and will see her later at the Tree Fort. Fionna and Prince Gumball talks for a while and Fionna asks if this was a date. Then Prince Gumball laughs and ask Fionna to be his girlfriend.
Fionna rushes to the Tree Fort and tells Cake it was a date, and the prince wanted to take her to the ball as his girlfriend. Cake then is suprised and dressed Fionna in a fancy dress and purse. Fionna thn asks how she's gonna fit her weapons inside the purse, Cake says to her that it's a ball and she doesn't need weapons. But Fionna didn't follow her and she just took her retractable sword anyway. They rush to the ball and sees Prince Gumball. Prince Gumball wanted to show Fionna something and took her to a room. Fionna asks is the room his bedroom. He started to take off his shirt and a drop a water fell from above. Fionna was shocked to see the real Prince Gumball trapped in a giant icicle on the ceiling. And it was just Ice Queen in disguise all along.
Fionna was enraged and took out her crystal sword, but Ice Queen laughs and turns the sword into a ball of ice around Fionna's hands. Fionna then yells to get the ice off and Cake hears her. Fionna rushes to the Ice Queen and hits her with the ball of ice. Ice Queen then unleashed a blizzard to blow Fionna, which allows her to break the prince free. Ice Queen gets knocked out by broken pieces of ice. and Cake bursts through the door. Seeing Gumball standing next to Fionna in her torn dress. Cake thinks it was Gumball and lunges at him. But Fionna stopped her and said it was the Ice Queen all along.
Ice Queen recovers and blasts her ice powers at Cake. Then Fionna punched the tiara off Ice Queen squelching with her powers. Fionna grabs Ice Queen and knocks her off the ground for "yanking her heart guts." Then Cake uses the tiara to bury Ice Queen in snow. Fionna tells Cake not to use the crown because she might get Ice Queen's crazy. Cake walks away mad, while Prince Gumball is amazed by Fionna and asked her on a date. Fionna said she decided she doesn't need a boyfriend, but she would love to date Ice King. Then the scene changes inside the Ice Kingdom and Finn and Jake trapped in ice, Ice King closed the book and said "the end," and asks. "What did you think of the fan fiction I wrote about you guys?"
Finn was the only one to response, because Jake's head was trapped in ice. Ice King threatens Finn by raising his hand, and said. "Tell me you thought it was good!" Then the episode ends with Finn saying the story was good.
- This episode got the most views in the show's history.
- It is confirmed that there will be a second episode of Fionna and Cake about Marshall Lee.
- This was the first episode that both Finn and Jake were only minor characters.