Bring a large pot of salted water to a rolling boil. Add the fettuccine and cook according to package directions until al dente, about 9-11 minutes. Reserve 1 cup of pasta water before draining, then set the cooked pasta aside. The starchy pasta water will help create a silky sauce later, so don't skip this step.

While the pasta cooks, heat the cooking oil in a large skillet over medium-high heat. Once shimmering, add the minced garlic and cook for 1-2 minutes until fragrant but not brown—burned garlic will taste bitter. Add the shrimp to the pan and cook for 4-6 minutes, stirring occasionally, until they turn opaque and pink throughout. I always use fresh minced garlic rather than jarred because it develops a much cleaner, brighter flavor in this quick-cooking dish.

Reduce heat to medium and add the butter to the skillet with the cooked shrimp, stirring until it melts completely. Pour in the lemon juice and add the lemon zest, then season with red pepper flakes, sea salt, and black pepper to taste. Stir everything together for about 30 seconds so the flavors combine. The butter will emulsify slightly with the lemon juice, creating a luxurious base for the sauce.

Add the cooked pasta from Step 1 to the skillet with the butter sauce and shrimp. Toss everything together gently, adding a splash of the reserved pasta water (about 2-3 tablespoons) to loosen the sauce if needed. Sprinkle the freshly grated Parmesan over the pasta and toss again until the cheese melts and coats everything evenly. I prefer freshly grated Parmesan because it melts smoothly into the sauce rather than clumping like pre-grated versions.

Divide the garlic butter shrimp fettuccine among serving bowls, making sure each portion gets shrimp, pasta, and sauce. Top with fresh parsley and an extra grind of black pepper if desired. Serve immediately while hot and creamy.