In a large pot of salted boiling water, cook the fettuccine according to package directions until al dente. Reserve 1 cup of pasta water before draining.
In a large skillet, heat olive oil over medium heat. Add minced garlic and sauté for about 1 minute or until fragrant.
Stir in the chopped spinach and cook until wilted, about 3-4 minutes.
Reduce heat to low and pour in the heavy cream. Allow it to simmer for a couple of minutes. Add the grated Parmesan cheese, lemon zest, and lemon juice. Stir until the cheese is melted and the sauce is creamy.
Add the drained pasta to the skillet. Toss gently to combine, adding reserved pasta water a little at a time until the desired creaminess is achieved.
Taste and season with salt and pepper. Add red pepper flakes if you like some heat.
Divide the creamy lemon spinach pasta among plates and garnish with fresh basil leaves.
Notes
For an elegant presentation, serve in a shallow bowl and top with additional Parmesan and a twist of lemon zest.