This is my son's 7th birthday cake. This is a chocolate cake with cookies & cream filling. Mainly buttercream but the mountain is a pound cake sculpted and covered in MMF. My sister "painted" it with Wilton icing colors. The mushrooms and banana peels are royal icing. I used some piping gel for the water along with the buttercream. The large yoshi egg is MMF. Modeled after Yoshi Falls--his favorite track on Mario Kart on Wii.