Preheat and prep: Set your oven to 425°F (220°C).
Line a sheet pan with parchment or lightly oil it to prevent sticking.
Trim the asparagus: Snap or cut off the woody ends. Aim for spears that are similar in thickness so they cook evenly.
Season the spears: Spread asparagus on the pan. Drizzle with olive oil, sprinkle with minced garlic, lemon zest from half the lemon, a good pinch of salt, and black pepper.
Toss to coat and arrange in a single layer.
Par-roast: Roast for 8–10 minutes, depending on thickness, until the asparagus turns bright green and starts to soften but isn’t fully tender.
Add the cheese: Pull the pan out. Sprinkle mozzarella evenly over the spears, followed by Parmesan. If using Gruyère or cheddar, scatter it on now.
For crunch, mix panko with melted butter and a pinch of salt, then sprinkle over the top.
Finish in the oven: Return to the oven for 5–7 minutes, until the cheese is melted and bubbling. For browned spots, switch to broil for the last 1–2 minutes, watching closely.
Brighten and serve: Squeeze the juice of the remaining half lemon over the asparagus. Add a pinch of red pepper flakes if you like heat.
Shower with chopped parsley or chives. Serve immediately while the cheese is hot and stretchy.