Bring 3½ cups of water to a boil in a large pot over high heat. While waiting for the water to boil, trim the asparagus and cut into 1-inch pieces, mince the garlic, grate the parmesan cheese, and chop the fresh parsley. Once the water reaches a rolling boil, add the orzo and stir occasionally to prevent sticking. Cook for 7-9 minutes until the orzo is just beginning to soften but still has a slight bite to it—I always use Delallo orzo because it holds its texture beautifully through cooking.
Add the cut asparagus pieces to the pot with the orzo and cook for exactly 3 more minutes—this timing ensures the asparagus stays tender-crisp while the orzo finishes cooking perfectly. Drain the entire contents through a colander, reserving the pasta water, and set aside.
While the pasta cooks, melt the butter in a large skillet over medium heat. Once melted and foaming, immediately add the minced garlic and cook for about 2 minutes, stirring frequently, until fragrant and just beginning to turn golden—be careful not to let it brown as it can turn bitter. Remove the skillet from heat and stir in the lemon juice and red pepper flakes, letting the residual heat gently warm these ingredients.
Add the drained orzo and asparagus mixture from Step 2 to the butter-garlic sauce in the skillet. Add the freshly grated parmesan cheese and toss everything together until well combined and creamy—the residual heat from the pasta will help the cheese melt into a silky sauce. If the dish seems too dry, add a splash or two of the reserved pasta water to reach your desired consistency. I find that freshly grated parmesan creates a much creamier, more luxurious texture than pre-grated varieties.
Taste the dish and season with salt and freshly ground black pepper to your preference. Divide into serving bowls, garnish with the fresh chopped parsley, and serve immediately with lemon wedges on the side for guests to squeeze over their portions for extra brightness.