This might sound crazy, but I'd suggest letting her do it, and let her have fun. You can, however, teach her that there needs to be a when, where, and what with, like letting her play at bath time, getting all gooey with something edible in a place that cleans up easy in the tub. You could even use it as a behavior reward, like, if you don't eat with a fork you won't get strawberry syrup in the tub tonight.
In the meantime, you may have to find a way to keep her out of things, and let her know that playing unsupervised is a responsibility that must be earned with appropriate behavior.
Might sound crazy, but I believe this fascination is a phase that will pass sooner if you allow it in a safe way, and rob it of its novelty. If it sounds wasteful or juvenile, i love the scene in Patch Adams where they put the lady in the pasta pool. I personally would go with marshmallows. Good luck.
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We are not so different from potted plants in that, if given everything we need to be properly nourished, the outcome can be incredibly contrary to when we are not. A flower won't grow in flour, and neither can we.