If you have frozen shrimp, place them in a zip-top bag into a bowl of cold water under a weight for about 30 minutes to thaw. Twist off the head, peel away the shell (you can leave the tail on), and run a paring knife along the back to remove any black vein.
Fill a pot with enough water to cover the pasta but slightly less than usual and set it over high heat. When it boils, stir in two teaspoons salt. While you’re waiting, set a large skillet over medium-high heat, add one tablespoon peppercorns, and shake the pan for two to three minutes until the pepper darkens and smells fragrant. Let them cool, then grind to a coarse mix in a mortar or spice grinder and return them to the skillet.
Mince one garlic clove, zest one lemon, and squeeze two tablespoons lemon juice. Having these ready keeps the cooking flowing smoothly.
Add one pound pasta to the boiling water, lower the heat to medium-high, and cook until al dente according to the package. Before you drain it, scoop out one and a half cups of pasta water, then drain the pasta and set it aside.
Return the pepper skillet to medium-low and pour in three tablespoons olive oil. Add the garlic and stir for two minutes until it sizzles. Raise the heat to medium, add the wine, lemon juice, and zest, and let it bubble for about a minute. Nestle the shrimp into the pan and cook two to three minutes per side until opaque. Transfer the shrimp with tongs to a bowl and cover. Turn the heat under the skillet to medium-high for 30 to 60 seconds to thicken the juices, then turn off the heat and cover the pan.
Return the drained pasta to the skillet with the pan juices. Pour in one-third cup of the reserved pasta water and use tongs to toss the noodles. Sprinkle in one-third of the cheese and two teaspoons crushed pepper, add a splash of water, and stir vigorously. Add another third of the cheese and another splash of water, stirring until the sauce becomes smooth and creamy. If it seems too thick, add more pasta water a splash at a time.
Divide the pasta among bowls, top each with the remaining cheese and three to four shrimp. Finish with a pinch of pepper and a scattering of parsley if you like.