You can make this with any type of rum, I prefer Bacardi Rum
Sweetened condensed milk acts as the crucial binding agent here, providing both the structural glue and the primary sweetness that holds the dry components together without requiring any thermal cooking process on a stovetop. Because dairy-heavy mixtures absorb ambient refrigerator aromas readily over extended periods, sealing these confections inside an airtight glass container lined with parchment paper ensures the delicate coconut exterior remains free from unwanted pantry odors while resting. Processing the marie biscuits down to a uniform sand-like powder rather than leaving coarse chunks prevents structural cracks from forming along the exterior surface during the final rolling stage. Allowing the formed spheres to rest in the refrigerator overnight permits the dry biscuit crumbs to fully hydrate from the moisture of the condensed milk, transforming a loose mixture into a firm, cohesive bite that easily holds its rounded shape at room temperature. For long-term planning, freezing these confections for up to two months works remarkably well when wrapped tightly in plastic wrap and transferred inside a heavy-duty freezer bag, though they must thaw slowly in the refrigerator for four hours before serving to prevent condensation from dissolving the outer coconut coating.