Spaghetti al Pesto

45 basil leaves (about a packed cup)
1/4 cup grated aged pecorino (Tuscan or Sardinian, because Romano is too sharp)
1/3 cup grated Parmigiano (increase this to 3/4 cup if you cannot find the pecorino)
2 cloves of garlic
2/3 cup olive oil
1/2 cup pine nuts
1/3 cup walnut meats (optional)
500 grams spaghetti
Salt and pepper to taste

Cooking Procedure:
1. If you have a marble mortar and wish to use it (purists say neither brass nor wood mortars will work), put the salt and pepper, garlic, nutmeats and basil in it and grind the mixture, firmly crushing the ingredients against the sides of the mortar, rather than striking sharp blows with the pestle.
2. When the mixture is ground, add the cheese, a bit at a time, continuing to grind, and when it is all worked in, add the oil in a slow stream, stirring with a wooden spatula. The resulting pesto should be smooth and creamy.
3. If you are using a food processor instead, chop the garlic, basil, nutmeats, and salt, being careful not to let the mixture liquefy, then transfer it to a bowl and stir in the grated cheese and the oil.
4. Cook a pound of pasta in lightly salted water, and just before you drain it stir two tablespoons of hot water into the sauce. Pour the sauce over the pasta and serve. The wine? The bitter sea tang of a good Vermentino would offset the garlic perfectly.
5. This sauce is also perfect for making lasagne al pesto, which are amazingly refreshing on a hot day, perhaps even more so when served cool.