Basic Basil Pesto

2 cups packed fresh basil leaves, (2-3 bunches)
1/4 cup walnut pieces, toasted (see Tip)
1/4 cup grated Parmigiano-Reggiano cheese
3 tablespoons extra-virgin olive oil
2 tablespoons water
1 large clove garlic, quartered
1/2 teaspoon salt
1/2 teaspoon freshly ground pepper

Place basil, walnuts, Parmigiano-Reggiano, oil, water, garlic, salt and pepper in a food processor; pulse a few times, then process until fairly smooth, or to the desired consistency, scraping down the sides occasionally.