Alton Brown provides a recipe for homemade peanut butter. Put 15 ounces of roasted peanuts in a food processor with 1 teaspoon of salt and 1 1/2 teaspoons of honey. Slowly add 1 1/2 tablespoons of peanut oil, and combine the ingredients until the mixture is smooth.
To make roasted peanuts from scratch, use 2 pounds of in-shell raw peanuts. Use Spanish peanuts, because they have a higher oil content than other types of peanuts. Rinse the peanuts with water, pat them dry, and toss them in a bowl with 2 tablespoons of peanut oil and kosher salt. Place them on a baking sheet in a single layer, and roast them for 35 minutes at 350 degrees. Let the peanuts cool off completely. Remove the peanuts from their shells and skin.
Combine homemade roasted peanuts with salt and honey in the food processor for about one minute. Scrape the sides of the food processor before adding the peanut oil. Put the lid back on the food processor, and slowly add oil to the peanut butter until the mixture is smooth. This takes about two additional minutes.
Store the homemade peanut butter in an airtight container. Keep it in the refrigerator for up to two months. Use the peanut butter to make peanut butter cookies, mousse or snack bars.