With a friend who has a severe nut allergy, can I use chocolate chips or something else?

Are pine nuts out of the question? You could use those, or toasted pepitas, to get that nice bit of crunch. ;o)

Yes! Jenny, our former columnist, has a chocolate chip version here: https://food52.com/recipes/19209-divine-gluten-free-chocolate-cookies

And I haven' frozen them but I imagine they'd freeze well, since Richard Sax's (flourless) Chocolate Cloud Cake freezes excellently.