Melt butter in heavy cream in a medium saucepan over medium heat, stirring occasionally.
Once butter has melted, stir in chocolate until melted and smooth. Stir in corn syrup, vanilla and cinnamon.
Remove from heat and cool to room temperature. Store in an airtight container in the refrigerator for up to 2 weeks. To reuse, heat in the microwave or on the stove.
Notes
*Use your favorite quality chocolate for the best tasting chocolate sauce.
**Corn syrup adds extra smooth silkiness but you can omit if desired and the sauce will still be wonderful.