Boil the pasta. Bring a large pot of salted water to a rolling boil. Cook the pasta until just shy of al dente. Reserve 1/2 cup of the starchy water, then drain.

Prep the asparagus. Snap off the woody ends, then cut the stalks into 1–2-inch pieces. Keep the tips intact for better texture and presentation.

Sauté aromatics. In a large skillet over medium heat, warm the olive oil and melt the butter. Add the shallot and a pinch of salt. Cook 2–3 minutes until soft, then add the garlic and cook 30 seconds until fragrant.

Cook the asparagus. Add asparagus pieces to the skillet with a pinch of salt and black pepper. Sauté 3–5 minutes, stirring, until bright green and crisp-tender. You want a slight bite, not mushy.

Build the sauce. Pour in the cream and bring to a gentle simmer. Reduce heat to medium-low. Stir in lemon zest and a pinch of red pepper flakes if using. Simmer 2–3 minutes to thicken slightly.

Add Parmesan. Off the heat, sprinkle in the Parmesan a handful at a time, stirring until smooth. If it seems too thick, loosen with reserved pasta water a few tablespoons at a time.

Toss with pasta. Add the drained pasta to the skillet. Return to low heat and toss until every strand is coated and glossy. Adjust with more pasta water for a silky, saucy finish.

Finish with lemon. Stir in lemon juice to taste. Season with more salt and black pepper. The sauce should taste bright, savory, and balanced.

Serve. Plate and top with extra Parmesan and chopped herbs. Add a final grind of black pepper for aroma.