In a microwave safe bowl, combine marshmallows and heavy cream.

Microwave for 15 seconds and then stir

Continue to microwave in 15 second increments, stirring every 15 seconds until all marshmallows are just about melted.  This will not take long at all.

Remove from microwave and add brown sugar and cinnamon.  

Stir and let cool for 2 minutes.

Enjoy!  OMG it is so good!!