A recipe for a traditional Italian pasta sauce made with fresh basil and pine nuts (pine kernels) . Pesto is remarkably easy to make and is simply stirred into hot pasta to serve.
This version uses both olive oil and butter. Butter is much more widely used in northern Italian dishes than in southern ones, and pesto is originally from Genoa (Genova) in the North West of Italy.
This article gives more history http://www.theatlantic.com/past/docs/issues/98aug/pesto.htm