I plan to make a birthday cake next week for my sons birthday on Sunday. I’m making a devils food cake sponge sandwiched which chocolate ganache & covered with cookies & cream buttercream. It’s to be decorated like a sheep using mini marshmallows & fondant. What I’m not sure of is 1. How far in advance can I make it? & 2. where should I store it ie fridge etc? The ganache will contain double cream as will the cookies & cream buttercream so I’m thinking it’ll need to be refidgerated? But I’m concerned that the marshmallows & fondant will go sticky & degrade in the fridge. Can anyone advise please?