I measured mine yesterday since I really had no clue.
5 cloves garlic
1/2 tsp. salt
3 oz. Reggiano
1/2 cup olive oil
1 bunch basil
All amounts are highly approximate depending on how much garlic you like and how big your bunch of basil is. I like hard-stemmed red garlic and fruity green olive oil such as Trader Joe’s Kalamata.
Put salt in a mortar, press the garlic into the mortar, mash with the pestle until smooth, cover with a layer of olive oil, and let sit for at least half an hour.
Microplane the Reggiano into the bowl of a food processor. Add the garlic mixture and oil and process, occasionally scraping down the sides of the bowl, until emulsified and creamy.
Pull the basil leaves off the stems and put into the bowl. Pulse, occasionally scraping down the sides of the bowl, until finely chopped. Do not process until the leaves exude liquid as that will make the pesto bitter.
Warm serving bowl, add drained hot pasta, and mix with pesto to taste, adjusting seasoning to taste.
If you have leftover pesto, cover with a layer of olive oil to prevent mold and store in the refrigerator. This can keep for months, though eventually the oil will go rancid.