Put the butter in a heatproof bowl, set over a small saucepan of simmering water to create a double boiler and melt it.
Add in the brown sugar, corn syrup, maple syrup, water, condensed milk, and cinnamon. Stir the sugar mixture and cook until the fondue is smooth, and all the sugar is completely dissolved.
Pour into fondue pot, and enjoy with your choice of dippers.