Remove the stalks from the spinach. This is done by folding the leave in half towards the front, exposing the stalk at the back. Grab it close to the stalk and pull it from the bottom all the way to the top. The stalk will be removed along with the fibre all along the leaf. For further reference watch the video above.
Wash the spinach leaves extra carefully because they tend to have dirt on them. Also, wash the basil leaves.
Cook the garlic with a bit of olive oil on medium heat for about a minute, stirring it constantly. Remove it from the pan and reserve.
On the same pan add extra olive oil and increase the heat to max.
Once hot, add the basil and spinach leaves all at once and immediately add about a teaspoon and a half of salt to them to help them stay intensely green. Mix and cook for only about 30 seconds or until everything is nice and wilted. Be careful not to overcook them because they turn dark and bitter.
Remove from the pan without the liquid they released.
Put all the ingredients in the blender, squeezing the leaves before adding them. Blend until smooth and creamy.
Heat in a pan and mix with cooked pasta. If needed, thin the sauce on the pan with the pasta's cooking liquid. Serve with parmesan cheese.