All that you need to make this is
Heavy whipping cream
Salt (optional if you want salty butter)
A jar (baby food jars are the perfect size if the littles are helping you out)
And about 10-20 minutes!
Fill your jar with however much whipping cream you want, I used about 6 oz, put the lid on and SHAKE, SHAKE, SHAKE!!! Once those fat starts sticking it will start to make the butter part and the liquid in there is buttermilk, great for using in your baked goods recipes so don't throw it out save it!!
Once it's done I drained the liquid to save until later and put the butter in a empty yogurt container!
I tried some straight away on my Udi's gluten free white sandhich bread toasted...YUMMMMMM!! I am a major butter lover and this was good!