Any nut can be used here in place of the peanuts. Just chop larger nuts roughly before incorporating them. If you have nut allergy issues, then try replacing the nuts with roasted pumpkin or sunflower seeds. Use a large pot to melt the marshmallows. Much larger than you think you will need. It will seem an absurd size whilst melting the marshmallows, but will make life much easier when you are trying to incorporate the popcorn.