Cake from Fionna and Cake from Season 2 Episode 1 with her mature anthro look when she goes to see Lord Monochromicorn. Her color palette is pretty tough for the AI to get right consistently, so I'm just going to share my best results on what I was able to generate. It mainly has issues coloring the top of her hair all yellow and one side of the wrist being a yellow stripe instead of a spot. It will get the character's likeness well at least. For the best results use the Illustrious XL personal merge checkpoint if you want character accuracy. WAI and Azure Starfire can work with good results as well.

Positive Prompts: FionS2, furry female, anthro, feline, cat, light-brown inner ear, white hair, yellow hair, multicolored hair, very short hair, black eyebrows, tiny eyebrows, black nose, light-blue sclera, black eyes, no pupils, white body, yellow belly, multicolored body, small breasts, featureless breasts, white tail, yellow tail tip, short tail, mismatched hands, yellow feet

Optional: backpack

If the tail appears way too short, then put "medium tail" instead and that should help. Also make sure to add "pumpkin, bag" in the negative prompts, so they don't generate randomly. This'll happen because in the episode she eats them from a bag and that causes the AI to generate them if you don't put it in the negatives lol.