Pour heavy whipping cream into your mason jar. Fill it between 1/4-1/2 full. The fuller it is, the longer the butter will take to make.
Screw lid onto mason jar to secure a tight fit.
Shake jar vigorously for 15-45 minutes (the more cream, the longer you will need to shake).
Once butter has separated from the cream and formed a ball, you are done.
Take butter ball out of jar and lightly rinse with water.
Enjoy on your favorite bread, rolls, or muffins!