Trenette al Pesto

2 bunches basil
3 tblsp pine nuts
2 garlic cloves
1 tblsp freshly grated sharp Pecorino cheese
1 tblsp grated Parmesan cheese
500 ml extra virgine olive oil
salt
2 or 3 potatoes cut into pieces
155 gr. green beans trimmed
410 gr trenette (thin ribbon pasta)
15 gr. butter
Immerse the basil leaves in boiling water for 1 minute. Wash and dry the leaves and shred them by hand. Put the basil in a mortar with the pine nuts and garlic and work until the mixture is reduced to paste. Add the cheeses and the oil a little at a time, still pounding, alternating the Pecorino and Parmasan and taking care that each addition is absorbed before adding more.
as the mixture thickens add a little more oil, and at the end taste and add salt, if necessary. the resulting pesto is a creamy soft sauce.
about 10 minutes before cooking the pasta cook the potatoes in boiling water until tender. while the pasta is cooking, cook the green beans in boiling salted water until al dente.
cook the trenette in boiling salted water until al dente. Before draining the trenette, stir the butter and a little of the pasta's cooking ater in de pesto sauce to dilute it and give it a creamier consistency.
Drain the pasta and vegetables , dress with the pesto and serve.

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