Is there anyway I could switch peanut butter to nutella or something? Severe peanut allergy, fine with hazelnuts. Neither almond butter or plain h...

What is flavorless oil?

I think tahini would be really good as a variation.

On the one hand, I would grind my own hazelnuts, similar to what foofaraw suggested, or even crush them finely in a bag (with a rolling pin or empty wine bottle) and add to the recipe. Why? because the nutella will have about double the carbs & sugar, and about 2/3 the fat, of the original.
On the other hand, why not? The original peanut butter measure only 1/2 cup and a substitution is unlikely to change the recipe much.
On the third hand, why not ask Molly directly?
http://mynameisyeh.com/contact/

If you have almond/cashew, you can grind them (roasted or unroasted, though roasted is tastier) in food processor to make almond/cashew butter. Cashew will have slightly more oil, so you probably need to reduce the oil a bit. http://wakethewolves.com/how-to-make-almond-butter/