On medium-low heat, whisk all the ingredients together (except mini marshmallows and graham crackers) in a medium saucepan just until everything is combined. The mixture should be warm, not simmering.
Remove from heat and chill whisked mixture on countertop until it comes to room temperature.
Follow your ice-cream machine's instructions from the manufacturer.
Mix in marshmallows and graham crackers when transferring to freezer proof container before transferring to freezer to set completely.
If you don't have an ice-cream machine, transfer mixture into a freezer-proof container and freeze for 5-6 hours, stirring every 30-45 minutes.
Recipe by Radiant Rachels at https://radiantrachels.com/malted-smores-ice-cream/