Lemon Butter Pasta Sauce
A glossy, bright sauce made from butter, garlic, fresh lemon, Parmesan and starchy pasta water that clings to every strand. It comes together in the time it takes to boil spaghetti.
- Prep
- 10 min
- Cook
- 15 min
- Total
- 25 min
- Makes
- 4 servings (about 1 ¼ cups sauce plus 1 lb pasta)
Steps
Before you start
- Finely grate the Parmesan on a rasp-style grater so it melts smoothly; pre-shredded cheese can turn grainy.
- Zest the lemons before juicing them, then measure the juice.
- Have everything measured and next to the stove: the sauce comes together in minutes once the pasta is cooked.
- Use a mug or heatproof measuring cup to scoop pasta water before draining; you will need about 1 cup.
Boil salted water
- Fill a large pot with 4 quarts (4 L) of water and bring to a rolling boil over high heat.
- Add 2 tablespoons kosher salt; the water should taste like mild seawater.
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Ready when: Water is at a full rolling boil
Cook the pasta
- Add the spaghetti and stir for the first 30 seconds so it doesn't stick.
- Cook 1 minute less than the package directions, usually 8 to 9 minutes, so it can finish in the sauce.
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Ready when: Pasta is flexible but still has a firm, slightly chalky center when bitten
Tip: Start the sauce in the next step while the pasta cooks, about 3 minutes before it is ready.
Melt butter, soften garlic
- In the 12-inch skillet, melt 3 tablespoons (42 g) of the butter over medium-low heat.
- Add the sliced garlic and the red pepper flakes if using.
- Cook, stirring often, for 1 to 2 minutes.
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Ready when: Garlic smells sweet and is pale gold at the edges, not brown
Tip: Burnt garlic turns bitter. If it colors quickly, lift the pan off the heat.
Reserve pasta water
- Just before draining, scoop out 1 cup (240 ml) of the starchy pasta water with a heatproof measuring cup.
- Drain the pasta without rinsing it.
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Ready when: Reserved water looks cloudy
Tip: Reserve it before draining. It is easy to forget and cannot be replaced.
Build the sauce base
- Pour ½ cup (120 ml) of the pasta water into the skillet with the garlic butter and add the lemon juice and black pepper.
- Raise the heat to medium and simmer for 1 minute.
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Ready when: Liquid is bubbling gently and smells bright and lemony
Toss pasta in sauce
- Add the drained pasta to the skillet.
- Using tongs, toss constantly for 1 minute so the pasta absorbs some of the liquid.
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Ready when: Pasta is coated and the liquid has reduced slightly
Emulsify with butter
- Remove the pan from the heat.
- Add the remaining 5 tablespoons (71 g) cold butter, a few pieces at a time, tossing until each melts.
- Add about ¼ cup (60 ml) more pasta water.
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Ready when: Sauce looks creamy and glossy, not oily or separated
Tip: Adding cold butter off the heat keeps the sauce from splitting.
Add Parmesan and zest
- Sprinkle in the Parmesan about ¼ cup at a time, tossing well after each addition.
- Add the lemon zest.
- If the sauce looks tight or clumpy, loosen with more pasta water, 2 tablespoons at a time, up to the remaining ¼ cup (60 ml).
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Ready when: Sauce is silky and coats the pasta, pooling only slightly in the pan
Tip: Cheese added over high heat clumps. Keep the pan off the heat.
Season and serve
- Taste and add salt, pepper or a squeeze more lemon if needed.
- Divide among warm bowls, top with parsley if using and extra Parmesan, and serve right away.
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Ready when: Sauce is glossy and bright; flavor is balanced between rich and tart
Tip: The sauce tightens as it cools, so serve immediately.
Good to know
Tips
- Strain the lemon juice so seeds and pulp don't dull the silky texture.
- Use the zest for aroma and the juice for tang; zest added at the end keeps its fragrance.
- Salt the pasta water well, because the sauce relies on it for seasoning, and taste before adding more since Parmesan is salty.
- Serve in warmed bowls; this sauce thickens quickly as it cools.
Storage & reheating
Best eaten fresh. Refrigerate leftovers in an airtight container up to 3 days. Not recommended for freezing, as the emulsion breaks. Reheat gently in a skillet over low heat with 2 to 3 tablespoons water or pasta water, tossing until creamy, 2 to 3 minutes.
Substitutions
- Parmesan cheese → Pecorino Romano. Saltier and sharper; use the same amount and reduce added salt.
- spaghetti or linguine → fettuccine or short pasta such as penne. Use the same weight; cook to the package time minus 1 minute.
- unsalted butter → half butter, half extra-virgin olive oil. Use 4 tablespoons each; add the oil at the start with the garlic for a lighter sauce.
- fresh flat-leaf parsley → fresh basil or chives. Same amount; add just before serving.
