In a medium saucepan, stir together the evaporated milk and sugar. Heat over low, stirring often, until the sugar is completely dissolved.
Whisk in marshmallow fluff, a couple of spoonfuls at a time, until melted and smooth.
Stir in chocolate syrup and peppermint extract.
Pour brewed coffee into a large mug. Add 1/4 c. creamer, stir, and top with whipped cream if desired. (You can add as much or little creamer as you like to your coffee - the more you add, the more it'll taste like the peppermint mocha from a coffee shop!)
Store leftover creamer in an airtight container in the refrigerator for up to two weeks.