Ingredients

• 1 lemon (zest it and reserve the lemon juice)
• 12 oz. spaghetti or other long pasta
• Kosher salt
• ¾ cup heavy cream
• 6 tbsp. unsalted butter
• 3 oz. finely grated Parmesan (about ¾ cup)
• Freshly ground black pepper

Instructions

1. 1Cook the spaghetti until al denté, reserving 1 1/2 cups of the cooking liquid
2. 2Meanwhile, to make the sauce- add ¾ cup heavy cream to pot with lemon zest and cook over medium heat, whisking often, until liquid is just beginning to simmer, about 2 minutes. Reduce heat to medium-low. Whisk in 6 Tbsp. unsalted butter, 1 Tbsp. at a time, until melted and sauce is creamy and emulsified. Remove from heat.
3. 3When spaghetti is al denté, add ¾ cup pasta cooking liquid to cream sauce and return to medium heat. Using tongs, transfer spaghetti to pot with sauce (it’s okay if a little water comes along with it). Cook pasta, tossing often and adding 3 oz. finely grated Parmesan (about ¾ cup) little by little, until cheese is melted and sauce is creamy, about 3 minutes.
4. 4Remove from heat and stir in 2 tbsp of the reserved lemon juice. If sauce looks tight, add more pasta cooking liquid (cream sauces tighten up very quickly as they cool, so it’s better to lean on the saucier side of things). Season with more salt, if needed.