Can I make this without heavy cream?
Yes. Swap the heavy cream for half-and-half for a lighter sauce. You can also use whole milk, but keep the heat low, do not let it boil, and lean harder on the pasta water to keep it silky.
Why did my sauce get clumpy or grainy?
Usually it is one of two things: the heat was too high when the cheese went in, or the pasta water was not warm enough to help emulsify. Keep the pan on low when adding Parmesan and add it gradually while tossing. Also, freshly grate Parmesan off the block if you can. Pre-shredded cheese often has anti-caking additives that can make melting less smooth.
What pasta shape works best?
Long noodles like spaghetti, linguine, or fettuccine are perfect. For short pasta, use rigatoni or penne and be generous with pasta water so the sauce coats the ridges.
Can I add protein or veggies?
Absolutely. Toss in baby spinach after the pasta hits the sauce to wilt, or add peas with a splash of pasta water to warm through. For shrimp or sliced chicken, cook it separately and add it at the very end so you do not overcook it while the sauce finishes. This sauce also loves roasted broccoli.
How do I keep the lemon from tasting bitter?
Zest only the yellow part of the lemon. If you hit the white pith, that is where bitterness lives. Also, add the lemon juice at the end so it stays bright.
