"Create a wacky, colorful, and fun birthday cake recipe inspired by Disney's The Little Mermaid with a Broadway/Musical Theatre twist. The cake should be playful and comedic in style, celebrating pansexual/2SLGBTQIA+ pride with vibrant rainbow colors and whimsical decorations. The flavor should be sweet and fruity, avoiding any spicy or hot ingredients. Include layers with different fruity flavors, bright rainbow frosting, and fun edible decorations like musical notes, seashells, and glitter. The cake should be suitable for a joyful birthday celebration."