I have a love-hate relationship with peanut butter. I’m talking about the good stuff, the real stuff, the stuff made with peanuts, maybe a touch of salt, and none of the more processed add-ins like sugar, palm oil, and emulsifiers—the stuff that also, as a result of its minimal ingredients, is prone to separating. That’s where the hate comes in. I usually give a jar my best stir when opening it and then hope for the best, until I inevitably get close to the bottom and find unappealing bits of dry nut butter.  Clearly, my stir-and-hope-for-the-best method isn't great, so I set out to find the best option for keeping nut butter combined until the very last spread. I tested nine commonly touted methods, and got a good arm workout in the process.…