Bring one gallon of water to a boil in a large stock pot.
Add 4.5 teaspoons of salt and pasta to water and bring back to a boil, cooking according to package instructions.
Do not overcook pasta - it is best served al dente
Reserve pasta water
In the meantime, heat ⅓ cup olive oil in a large saute pan.
Season shrimp with salt and pepper and add to pan.
Cook shrimp for 4 to 5 minutes, 2 minutes on each side.
Using slotted spoon, remove shrimp from pan and set aside
Add the garlic to the pan and cook until fragrant, about 1 to 2 minutes - do not brown!
Add white wine and cook over medium-high heat until reduced by half, about 3 to 4 minutes.
Add the remaining olive oil, lemon juice, zest, and crushed red pepper and cook for another minute.
Drain pasta and then toss with spinach, shrimp, and sauce.
Add a bit of reserved pasta water if desired.
Garnish with fresh parsley if desired.