Pesto can have many variations from the type of basil you use to the type of nuts. So don't feel bound to use the typical ingredients. I've also seen pesto made out of parsley, cilantro, arugala, etc.
My pesto sauce uses basil and roasted walnuts. I actually prefer the walnut over the traditional Pinole nut (pine nut) but do make it at times when I have them handy. I've also used almonds.
Here is my no measurement pesto, depending on how much of the main ingredient you have (basil) will depend on how much other ingredients you use. Also depends on your love of garlic, etc.
~Basil - a lot of it
~Garlic - 2+ cloves
~Parmigiano Cheese - 1/4 cup
~Pecorino Romano - 1/2 cup
~Walnuts - roasted - 1 cup
~Extra Virgin Olive Oil
In a food processor put in basil, garlic, cheeses, and half the walnuts. I like to have a bit of bigger pieces of walnuts in the sauce so I add the remaining walnuts when I have only 2-4 pulses left to go on the food processor.
Process those ingredients until it comes together. Stop and scrap the sides of bowl if needed. Once items are mixed and minced really well drizzle in the olive oil while continuing to blend. Pour in oil until it's the consistency of a thick cream soup. Add remaining walnuts and pulse until they are small pieces but not pulverized.
I like to make a big batch of pesto and put it in small Tupperware containers to put into the freezer to use during the rest of the year. I put a thin layer of olive oil on top and leave room in the container for it to expand during the freezing process.
Pesto Sauce Uses:
~obvious one, over pasta
~add a couple of heaping tablespoons to a béchamel or cheese sauce for a pasta or lasagna
~spread on bruschetta
~make it thinner and use as a dip with pieces of good Italian bread