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 - March 11, 2020 0 1800 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.