Today my son and I made peanut butter. It is super easy. I bought a pound of pre-roasted (but unsalted) peanuts this morning. From what I had read on the web, you simply need to chop them up in a food processor or blender. The blender takes longer, but works just fine.
Keep chopping/processing/blending until it is smooth and creamy. You need to add a touch of salt to taste.
You could add a bit of peanut oil at the beginning of the process to speed everything up, but it is not necessary. We did a batch with and without the oil and preferred the batch without oil better (then we mixed them together).
You definitely want to salt it just a touch. It was pretty nasty before adding salt. Some people have recommended a bit of sugar too. I guess you can. For me it was fine without. I mostly use peanut butter on my pancakes, therefore I will be putting some syrup on there too. Or if you are using it for PB&J sandwiches, you probably don’t need the sugar as the jelly will have plenty.
The pound of peanuts (shelled, roasted and peeled) cost about $1.50. I am sure that amount will vary quite a bit from place to place. It made more than $1.50 worth of peanut butter. It should be about as healthy as you can get. No preservatives are added, therefore you will want to keep it in the fridge. It is supposed to keep for about 2 months, but peanut butter never lasts that long in our house. If the oil separates out, just stir it back in before using.
And, no, you don’t add any butter to the process.