Put basil, Parmesan, cashew nuts, garlic cloves, salt and pepper into a food processor and whiz into a paste.
If you like your pesto chunky then whiz for a shorter time than you would if you want it smoother.
Transfer paste into a container and slowly drizzle in olive oil, mixing all the time till pesto is saturated. I add in about 1/2 cup (100mL) for this amount of pesto but OH happily adds in more.
Adjust seasonings to taste and then serve.
Notes
Basil Pesto Sauce Tips
This is a basic sauce recipe; feel free to adjust ingredients as necessary.
For a smoother basil pesto sauce blend for longer, blend less if you prefer a chunkier sauce.
If you want it to be more of a sauce then add a little bit more oil.
To roast the nuts, bake them in the oven at fan-assisted 140C/ 160C/ 350F/ Gas 4 for about 15 minutes.
Using roasted garlic instead of raw adds additional flavor to this.
If using raw garlic in pesto is to crush it first, as you don't want to end up with large chunks of garlic when eating it.