It is pretty simple to make. You throw the following ingredients into a blender or food processor and blend: 1 cup (or so) of olive oil, 1/2 to 3/4 cup of pine nuts, 2 or 3 cloves of garlic. Then, in small handfuls, you add the basil, while continuing to blend. I end up using 1 big-ass bowl of it. Because we never know how much basil we'll be cutting, the recipe varies. Before serving, you can mix in 1/2 cup of grated Parmesan to every cup of pesto.
On a good day, we'll have fresh garlic and enough cuttings to yield over 2 cups of pesto. Today was a good day. You can store the pesto (if you have any left-over) in the fridge under, in a closed container, under a small layer of olive oil.