In a large saucepan add about 5 liters of water and bring to a boil. Once the water has boiled, add 2 tbsp salt and after 1 minute the pasta. Boil until the pasta becomes al dente.
In a small pan, over medium to high heat, roast the pine nuts for about 5 minutes.
In a mortar add the roasted pine nuts and garlic cloves. Using a pestle, mash them until there are no large chunks.
Finely chop the basil and spinach with a sharp knife. Add the vegetables, a little at a time, to the mortar, and continue mashing. Gradually add the olive oil, as needed, continuining to blend into a paste.
Once the sauce is smooth stir in the parmesan and any remaining olive oil. Season with salt.
If the pesto is too thick, add 2-3 tbsp from the water that boiled the pasta.
In an serving plate add the sauce and the pasta on top. This will make it easier to mix.
Serve with extra grated parmesan and fresh basil.