I'm sure in time Pitaya can do it. But I wouldn't blame Wanda for it.

An entire cake to Wanda is the equivalent comparison of one being compared to the size of a regular snack cake, and given Wanda’s belly that could potentially bigger than Pitt herself is currently (though maybe not for long as she appears to be quite fatter and gluttonous with sweets as of lately as well), it would probably take a lot of cakes to get Wanda her fill.

To Wanda, an entire cake is the equivalent of a light cookie.

The amount of calories she’d be consuming now as a Delphox in comparison to Pitt’s Braxien size is really saying something for sure. Just imagine how much more gluttonous Pitt will get when she evolves into a Delphox in her future, or even yet, might be MORE gluttonous than her mother ever was. Either way, they’ll both fill out the roles of having proof of having Snorlax genes in them physically when they balloon to the size of actual Snorlaxs.