In a blender, add your baby spinach, basil, garlic, olive oil, Parmesan cheese, salt, pepper and lemon, and blend everything together until a thick and creamy paste is formed.
Taste the pesto sauce and add more salt and pepper if required, then set aside.
Next, boil a pot of water and generously season with salt. Once the water is boiling rapidly, cook your spaghetti according to the package instructions and remove it from the pot once al dente.
Place the cooked spaghetti in a large bowl, pour the pesto sauce in, and mix everything until well combined. Add a ladle or two of pasta water while mixing to create a luscious sauce.
Once everything is well mixed, plate your pasta, top it off with smoked salmon bits or any meat of your choice, and lastly sprinkle on some extra Parmesan cheese.
I followed it exactly as written and it turned out perfectly.