For non-hydrogenated (separating) peanut butter: Place the jar in a pan of warm water on low heat and let sit about an hour or so until it warms up. Then it's really easy to stir with a table knife until well mixed--it takes only a couple of minutes. At least refrigerate until it cools off, or it will separate again. I use Adams peanut butter; I don't want peanut butter that contains sugar or is hydrogenated.