Pre-heat the oven to 180ºC.
Spread the peanuts out in a single layer on a baking tray and roast for 15 minutes.
Taste a peanut (carefully it will be hot) and if it doesn't taste like a roasted peanut carry on roasting for a little longer and taste again.
Once the peanuts are ready, allow them to cool.
Pop the peanuts into a food processor and blend until the peanut fragments are the size you'd like in your peanut butter.
Remove a few tablespoons (amount depends on how much crunch you want in your peanut butter) and set aside.
Continue blending the peanuts, stopping periodically to scrape down the sides (patience needed unless you have a high powered blender) until you achieve the consistency of peanut butter (having a little taste will confirm this too).
Finally fold in the peanuts fragments and place in a 500 ml sterilised jar.
Store in a cool dark place.