Friend or not, she should return your package if she's not going to pay for it. The scenario that comes to mind is me ordering a cake plateau for a wedding that did not arrive in time. I had to scramble to find an alternative and then I had no use for the original. If I keep it, I have to pay for it regardless. This is life. But I can mark the package "Return to Sender" and get my refund.

At least you'd get to EAT the cookies