Saut, the liver in the butter; when cool, remove from pan & chop coarsely. In a blender or food processor combine the basil, garlic, walnuts, chives, cheese, salt, pepper, and 1/4 cup of the olive oil. Blend at low speed until a pur, e consistency is achieved. Slowly add the remaining oil, blending at low speed until the oil is completely incorporated and the consistency is that of whipped cream. Add the liver and blend another 5 seconds and no longer; the texture of the liver should be discernible. Serve as a spread for crackers or as a sauce for spaghetti; if the latter, increase the oil to 1-1/2 cups.