Pour in the cream and mix on high using a wire whisk attachment. Cover with a tea towel or splash guard to contain any mess.
The cream will first start forming peaks (feel free to stop at this point if you want some incredible whipped cream). Then, the butter will start to solidify and separate from the buttermilk. This usually takes anywhere from 5-10 minutes.
Once you see clumps of butter, turn off the mixer and remove the bowl. Press the butter against the sides with a large wooden spoon or spatula.
Pour everything into a mesh strainer with another bowl or jar with funnel underneath.
Add the salt and use a wooden spoon, spatula, or your hands to get as much buttermilk out as possible.
Form into a ball and rinse with cold water until it runs clear. Spread into a mold or store in a lidded container.