Lemon Asparagus Pasta

From the garden

• 1 lb asparagus, woody ends snapped off, cut into 2-inch pieces
• 3 cloves garlic, thinly sliced

From the pantry

• 12 oz spaghetti or linguine
• 2 lemons · zest of both, juice of one
• ¾ cup parmesan, finely grated, plus more to serve
• 2 tbsp butter
• 2 tbsp olive oil
• red pepper flakes (optional) · a pinch, to finish
• salt · to taste
• black pepper

1. Boil the pasta in well-salted water until just shy of al dente. It finishes in the sauce. Before draining, scoop out and reserve a full cup of the starchy cooking water.
2. While the pasta cooks, heat the olive oil in your widest skillet over medium-high. Add the asparagus with a pinch of salt and cook, tossing occasionally, 3–4 minutes until bright green and crisp-tender with a few browned spots. Add the garlic for the last minute, until fragrant but not colored.
3. Drop the heat to medium-low and add the drained pasta, butter, lemon zest and juice, and a good splash of the reserved pasta water.
4. Toss constantly while raining in the parmesan. The starch, butter, and cheese emulsify into a light sauce that clings to the noodles. Loosen with more pasta water, a splash at a time, until it's silky rather than sticky.
5. Season with black pepper and salt to taste and serve immediately with extra parmesan and red pepper flakes at the table.