Two different methods, one using a blender, the other, a food processor:

PESTO 

Into the container of a Blender put --

1/2 cup olive oil

1/4 to 1/2 cup pine nuts (to taste)

3 garlic cloves (or more, to taste)

1 1/2 cups basil leaves (well-washed, dried, and picked over, no stems; tightly packed)

1 tsp. salt (may omit)

Blend for 1 to 1 1/4 minutes or until the ingredients are reduced to a paste.
Add 1/2 cup grated Parmesan, Pecorino, or Sardo cheese (or a combination of the three) and blend again briefly.
Toss sauce lightly with about 3/4 lb. spaghettini and serve with additional grated cheese.  (This is the point to pull out your pricey Parmigiano-Reggiano and the nifty table grater you've been saving.)

You can use pesto with rice or gnocchi or even on baked potatoes.  Also good with hot vegetables, e.g. green beans.

You can make this with fresh parsley instead of basil, which of course changes the flavor greatly.  Also, you can use walnuts or shelled sunflower seeds if pine nuts are not available.

IF USING A FOOD PROCESSOR --

Put into container

                        3 cloves garlic, peeled

                        1 tsp. salt (may omit)

                        1/2 cup pine nuts

Process briefly.

Add 2 c. firmly packed basil leaves.
Add 1/2 cup olive oil slowly through tube.-- while processor is running
Add 1/2 cup parmesan/Romano and process briefly.