Thoroughly rinse the asparagus under cool running water and gently shake off excess moisture. Hold each stalk near the base and snap off the woody ends, allowing them to naturally break where they become tender. Discard the tough ends.

Arrange the trimmed asparagus in a single layer on a large, rimmed baking sheet. Drizzle with olive oil and sprinkle evenly with salt and freshly ground black pepper. Lightly roll the spears back and forth to ensure an even coating of oil and seasoning.

Squeeze the juice from half a lemon evenly over the asparagus, infusing it with a fresh citrusy brightness. Thinly slice the remaining half of the lemon into rings and arrange them along the upper third of the asparagus. Distribute the sliced butter evenly down the center of the asparagus, allowing it to melt into the spears as they roast.

Transfer the baking sheet to a preheated oven at 400°F. Roast for approximately 10 minutes, or until the asparagus is tender yet still slightly crisp. Remove the baking sheet from the oven and switch the oven setting to Broil.

Evenly sprinkle the asparagus with shredded Parmesan cheese, focusing on the center to create a flavorful, cheesy topping. Return the pan to the oven and broil for an additional 2-3 minutes, or until the cheese is melted and lightly golden.

Serve immediately while warm, ensuring every bite delivers the perfect balance of buttery richness, zesty citrus, and savory Parmesan.