There are many interpretations of the classic Italian pasta dish, spaghetti al limone, or spaghetti with lemon. Some call for an Alfredo-like sauce made with heavy cream, butter and Parmesan, while others rely on just olive oil, lemon juice, Parmesan and starchy pasta water. This particular recipe, which adds sautéed shrimp, white wine and fresh tarragon to the mix, leans toward the simpler preparation. Without the addition of heavy cream, the sauce has a brighter lemon flavor, which works beautifully with the delicate brininess of the shrimp. Tarragon adds a fragrant note and a bit of complexity to an otherwise fairly straightforward dish. Finally, if there were a time to spring for freshly grated Parmigiano-Reggiano, this would be it. In an uncomplicated recipe like this one, the quality of each ingredient is paramount.