Mrs. Robertson's Delightful Pesto Sauce

Blend:
2 cups fresh basil
1/2 cup olive oil
2 tablespoons pine nuts
2 cloves garlic crushed and peeled
1 teaspoon salt

Stir in (not blend, makes a big difference):
1/2 cup grated parmesan
2 tablespoons pecorino

Stir in vigorously:3 tablespoons softened butter