Add cream to a large bowl or the bowl of an electric mixer. Beat on high for exactly 7 minutes. It will mix until a ball of butter forms. Once ball of butter has formed, drain liquid (buttermilk). Reserve for another use.
Add jam, cinnamon, and salt. Mix until combined, about 30 seconds on high.
Put butter into a covered jar and refrigerate up to 1 week. Enjoy with fresh bread.
Notes
Cover stand mixer to avoid splashing. Use the whisk attachment. The cream will turn to whipped cream, then will seem to get liquidy. Right before the 7-minute mark, the cream will come together to form butter (clumps or a ball).