Over medium heat In a saucepan, melt the butter, brown sugar and maple syrup. Stirring constantly bring it up to a boil.
Reduce the heat to medium-low and simmer it for about 4-5 minutes, until the brown sugar has dissolved well.
Take the syrup mixture off of the heat and let it cool to room temperature. Do not cool in the fridge as the butter will solidify and the icing will be lumpy.
Take the cooled syrup and pour it into a mixing bowl.
Slowly beat in the powdered sugar, cream and maple flavoring. Beat it until smooth and fluffy. If the icing is a bit too runny, add more icing sugar a tablespoon at a time until you get the consistency you need.
Use immediately to frost cookies, cupcakes or a cake!
Notes
If you have any leftover frosting it can be stored in the fridge for up to 5 days, just press plastic wrap onto the surface so a skin does not form and store in an airtight container. When you want to use it just let it warm to room temperature and whip it until smooth again.