Tip: To prevent splattering your entire kitchen, place a moist tea towel over the entire mixer while running.
Once the butter has formed (like above pic) just pour out the milk that is left. You can either save this milk (it's basically non-fat milk at this point) or you could toss it. Then start rinsing out the butter. . .
Continue to rinse the butter with cold water until the water comes out clean. (The above pic was almost there.)
Then form into whatever shapes you'd like! I did half of this batch as a large stick of butter, and the rest as teaspoon scoops. (Courtesy of my cookie scooper.)
Enjoy! You can either add salt, honey or just leave it as unsalted butter! But whatever you do, please enjoy! :)