Heat the oven to 180C/350F/gas mark four and spread the nuts out in one layer on a baking tray.
Roast for about 10-20 minutes until evenly browned. Allow to cool completely.
Whiz in a food processor to coarse crumbs then, if making crunchy peanut butter, scoop out a quarter and set aside.
With the motor running, add the oil, then whiz again, pausing to scrape down the sides if necessary, until you have a smooth, creamy texture.
Add any flavourings and taste, then stir in the reserved nuts and spoon into a jar.
It will keep in the fridge for a couple of months.
