In a large pot of salted boiling water, cook the spaghetti or fettuccine according to package instructions until al dente. Reserve 1 cup of pasta water, then drain the pasta and set aside.

In a large skillet over medium-high heat, add 1 tablespoon of olive oil. Once hot, add the shrimp, seasoning with salt and pepper. Cook for about 2-3 minutes per side until they are pink and opaque. Remove from the skillet and set aside.

In the same skillet, add another tablespoon of olive oil. Toss in the minced garlic and asparagus. Sauté for about 4-5 minutes until the asparagus is tender but still crisp.

Return the cooked pasta to the skillet, along with the shrimp. Pour in the lemon juice and add the lemon zest, red pepper flakes (if using), and remaining tablespoon of olive oil. Gently toss everything together, adding reserved pasta water until you've reached your desired sauce consistency.

Taste and adjust seasoning if needed. Serve immediately, garnished with freshly grated Parmesan cheese and chopped parsley on top.