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.
Remove the fondue from the heat and add the vanilla. Stir to combine.
Pour into fondue pot, and enjoy with your choice of dippers.
Notes
Make-ahead: Can be made up to 3 days ahead and reheated before servingStorage: Store leftover caramel in an airtight container in the refrigerator for up to 1 weekReheating: Reheat gently in microwave (15-second intervals) or double boiler until smoothIf too thick: Stir in 1-2 tablespoons of milk or creamApple tip: Pat apple slices dry before dipping so caramel sticks properly