One of the most obvious substitutes for marshmallow creme is whipped cream. It's like the cool, creamy cousin of marshmallow creme - similar, but with its own unique vibe. You can also use dulce de leche, which is like caramel on steroids (in a good way, of course!)!
Another classic substitute is Nutella - yes, you read that right! The popular chocolate-hazelnut spread can add a rich, chocolatey flavor to your treats. Just be warned: it's like a chocolate bomb went off in your kitchen (not that we're complaining)!