Spaghetti con Pesto

1. Combine basil, pine nuts, parsley and garlic in processor or blender and puree; add oil and butter gradually in a slow, steady stream until mixture is the consistency of mayonnaise.
2. Add white pepper and salt to taste.
3. Combine pesto sauce and cooked spaghetti in a large shallow serving bowl and toss well.
4. Serve immediately with parmesan cheese.
5. Finely chopped walnuts substitute for pine nuts.
6. The sauce can be frozen.