Pop your nuts in a food processor and blitz until the nuts turn from lumps to flour. Continue to process and the nut flour will start to release oils and turn to nut butter. Depending on your processor and the amount of nuts you are using, you may need to stop from time to time to scrape the sides of the processor.
Sterilise a jar and it’s lid by pouring boiled water inside. Allow to cool, dry, then transfer your nut butter to the jar. Seal and refrigerate. Homemade nut butter keeps for several weeks.