Roast the peanuts (Optional). If you are using raw peanuts, roast them first before processing. Set the rack in the center of the oven and preheat it to 180 °C/ 350 °F. On a baking sheet with a rim, scatter the nuts in a uniform layer. Toast until lightly golden-brown, glossy with oil and beginning to smell nutty, for about 10 minutes. If you prefer raw nut butter or are using pre-toasted nuts, you may omit this step.
Place the roasted peanuts in the food processor fitted with blade attachment or blender.
Pulse the nuts a few times, about 6 to 8 times in the beginning to break them up.
Optional. If you want to make crunchy peanut butter. Remove 1/2 cup of the chopped nuts at this stage and set aside.
Pulse the nuts on high speed for a minute. It will appear to be like a wet sand after 1 minute of continuous, high-speed processing. Pause the machine and scrape the bowl's sides and bottom.
Process for another 1 minute on high speed. The butter will then begin to clump at this point. Even though it isn't quite peanut butter, it is getting there! Note: Pause the processing every after a minute.
Pulse on high speed for another minute. The butter will be shiny and smooth at this point, like very thick peanut butter. Note: the equipment might heat up due to processing. If the machine starts to struggle at any point, stop for 10 minutes and let it cool down.
Add the salt, sweetener and oil (if using). Also, if you are using other add-ins, you can combine at this step.
Process for another 1-2 minutes on high speed. Process it until it is completely runny. Despite being quite runny at room temperature, it thickens considerably after being chilled.
Optional. If you set aside any nuts for chunky peanut butter, add them now and pulse a couple of times to combine.
Transfer the peanut butter in a jar with cover.
Serve as spread with your favorite bread or use as ingredient in making your dessert or sweets.