Once you've made it and know what it's supposed to look and smell like, move to the oven.
Preheat your oven to 250. Pop anywhere from 1 to 3 pounds of unsalted butter in a dutch oven (an enameled cast iron is best for this, if for no other reason than having an off-white interior) and cook uncovered.
After a couple hours, check on it. If it's still bubbling a lot, that means there's still water in the oil, so continue to cook until the bubbling has subsided and you see those marvelous little browned bits at the bottom of your dutch oven.
Once it's where you want like it, take out of the oven and strain through a double layer of cheesecloth.
It'll keep in the fridge for several months.