Just came back from a dinner with my business partners hosted by Anatole. When the dinner was almost over he said, “Man, I forgot to put the red caviar on the table”. Red caviar is also known as salmon roe.
I said, “OK, let’s get some, but we need bread and butter”. After that I went on talking about that good tasting Amish butter I’ve enjoyed last month in Pennsylvania. Anatole replied, “It’s easy, I’ll make you a good butter in two minutes.” Then he poured some heavy cream in a cup and turned on the blender.
Two minutes later we’ve enjoyed the butter better than the one I bought at the Amish market.
I always knew that Anatole thinks out of the box, but not to this extent!
yakovfain.com 
Your friend probably grew up with the grandma and learned all grandma’s recipe while watching her. The most important part – he remembers it and he USES IT.
You can do this just as easily without power tools, too. Pour heavy cream into a sealed rubber box such as Tupperware, and simply shaking it for a few minutes. The butter will separate from the whey and you’ll have a little ball of butter at the end. Kids love it.