Place heavy cream in food processor or blender. Hit blend and watch your appliance do the work. You will see the mixture changes in both consistency and color over about 2-3 minutes.
Continue to mix until cream separates into butter and butterfat. Drain off butterfat, which is now your buttermilk.
Do this again until there is no more liquid to drain, only solids.
The solids are butter, fold in a little salt and use the liquids as buttermilk.
If you've tried this technique, come back and let us know how it was in the comments or ratings!