This artful combination of green pasta and pink shrimp will make you feel all elegant even if you are just wearing your gym clothes!
In a large pot over moderately high heat, combine 4 quarts of water and salt. Bring to a boil, then add fettuccine and cook to one minute short of al dente according to the package instructions.
Drain pasta and set aside, reserving 1/2 cup of pasta water.
Add the drained pasta to the pot in which it was cooked along with the reserved pasta water. Turn the heat to medium and add the pesto, stirring well until the pasta is warm. Add the spinach or julienned kale and cook for two to three minutes, stirring constantly until the spinich or kale is just wilted. Remove pan from the heat and add the remaining 2 tablespoons of butter. Stir until everything is well combined.
Turn the pasta into a large, warmed bowl and pour the shrimp mixture over the top. Garnish with freshly grated Parmesan cheese.