Unicorn Birthday Cake : Sugared Pumpkin on Instagram: “Why decide on a theme when you can have both your favourites on one cake?! This was half unicorn, half mermaid for a lucky birthday girl.” By Luana - December 21, 2019 0 1954 Unicorn Birthday Cake : Image : Description Why decide on a theme when you can have both your favourites on one cake?! This was half unicorn, half mermaid for a lucky birthday girl.