Step 1: Cook the pasta: Bring a large pot of salted water to a rolling boil. Add the pasta and cook according to package directions until al dente. Before draining, reserve at least 1 cup of the starchy pasta cooking water. Drain the pasta and set aside.
Step 2: Sauté garlic and asparagus: In a large skillet or Dutch oven, heat the olive oil over medium heat. Add the minced garlic and sauté for about 1 minute until fragrant, being careful not to let it brown.
Step 3: Add asparagus: Add the trimmed and cut asparagus pieces to the skillet. Sauté for 3-5 minutes, stirring occasionally, until the asparagus is bright green and tender-crisp. You want it cooked but still with a slight bite.
Step 4: Create the creamy sauce: Pour in the heavy cream and 1/4 cup of the reserved pasta water into the skillet with the asparagus. Bring to a gentle simmer, stirring constantly, allowing the sauce to slightly thicken.
Step 5: Combine with pasta and finish sauce: Add the drained, cooked pasta to the skillet. Stir in the lemon zest and about half of the lemon juice. Add the grated Parmesan cheese and toss everything together until the cheese is melted and the pasta is evenly coated in the creamy sauce.
Step 6: Adjust consistency and season: If the sauce is too thick, add more reserved pasta water, 1-2 tablespoons at a time, until it reaches your desired creamy consistency. Season generously with salt and freshly ground black pepper to taste. Add more lemon juice if you desire a brighter flavor.
Step 7: Serve: Serve the creamy lemon asparagus pasta immediately. Garnish with additional grated Parmesan cheese and fresh chopped parsley, if using. Enjoy!