The bestest recipe is the one on the Cream of Tartar box. It's never failed me. I had an epic play dough fail and the BB community pointed me in that direction and I'm now a champion Play dough maker! ( I halve the recipe)
It lasts for absolutely ages.
I'm sure she'll love it. And what does it matter if she eats a bit! At least you know what's in it.

Pm'd you the recipe. I'm too lazy to rewrite it!