Put on a large pot of salted water and cook the pasta al dente. Drain and reserve a bit of the cooking liquid.
In the mean time heat a large frying pan with a bit of oil. Add the onion and bake until translucent. Add the garlic and briefly bake that too.
Now add the spinach in stages. Once one batch is wilted add the next batch.
Add all the spinach into a high measuring cup and add the parmesan cheese with a bit of the basil. Add a spoonful of the cooking liquid from the pasta if you want. Using a stick blender puree the spinach until smooth. Taste and add pepper and salt if needed.
Add the pasta back into the pan and add your spinach sauce. Shake it around so all the pasta gets covered with the spinach. If it is too dry add a bit of the cooking liquid.
Serve the pasta hot with the toasted pine nuts, extra parmesan cheese and fresh basil.
Disclaimer
The nutritional values above are calculated per portion. The details are based on standard nutritional tables and do not constitute a professional nutritional advice.