The cake model of product strategy is actually two different models for how to evolve and improve the scope of a product over time.
Most organizations plan out new products and experiences using a dry cake model. They start with cake, then maybe add some filling, and then plan to add the icing as the final step. It makes sense from an operational perspective. But there are problems with this model from both the customer's viewpoint and from a competitive perspective. Cake with no filling or icing isn't that appealing. Plus, anyone can make just cake.
A better model for planning new experiences is the cupcake model. Start with something small, but very desirable. Move on to additional releases that also balance the expected (cake) with enough filling and icing to create a great experience that sets you apart.