Start by lining your muffin tin with cupcake liners. This will help you easily remove the Mallo Cups once they are set.
In a double boiler, combine the milk chocolate and coconut oil. Stir occasionally until melted and smooth.
Spoon about a tablespoon of the melted chocolate into each cupcake liner, spreading it up the sides to create a shell. Place the muffin tin in the refrigerator to set.
In a medium saucepan, combine the corn syrup, granulated sugar, and water. Heat over medium heat until the sugar is dissolved and bring to a gentle boil.
In a separate bowl, use an electric mixer to beat the egg whites and cream of tartar until soft peaks form. Pour in the sugar mixture while continuing to beat, then add vanilla and salt.
Fold in the marshmallow fluff and flaked coconut into the egg white mixture until combined.
Spoon the marshmallow filling into each chocolate-coated shell, filling them about three-quarters full. Smooth the tops with a spatula.
Pour the remaining melted chocolate over the marshmallow filling, ensuring each cup is fully covered.
Return the muffin tin to the refrigerator and chill for at least 1 hour until completely set.
Once set, remove the Mallo Cups from the muffin tin by peeling away the liners. Store them in an airtight container or share with friends!
