Mix together the flour, poppy seeds, and salt in a large bowl. Transfer the flour mixture to a working surface, making a large pile, then make a deep well in it. Crack the eggs into the well and gently beat with a fork. Begin to pull flour into the egg mixture from the edges of the well as you beat until it becomes too difficult to keep working with the fork. Use your hands to combine the rest of the dough, then knead until it is a soft, smooth ball. Set aside to rest under a kitchen towel for 30 minutes.
Transfer dough to a lightly floured work surface. If you have a pasta roller, roll out pasta using the third thinnest setting. If you don’t have a pasta roller, use a rolling pin to roll out until you have one smooth sheet of pasta about a few millimeters thick. Using a pasta cutter wheel, cut the pasta into long thick strips about 2.5 centimeters wide. Reserve pasta on baking sheet dusted with flour until ready to cook.
Put a large pot of salted water on to boil.
For the toppings:
Heat the butter in a frying pan over medium heat, then add sage leaves and fry until crispy, then remove to a paper-towel lined plate. Add the prosciutto and cook until crispy, about three or four minutes, then remove to a paper towel-lined plate.
Boil the pappardelle noodles until al dente, then drain.
Add pasta to same pan with flavored butter. Crumble sage leaves and crispy prosciutto over pasta, reserving some for garnish. Add a small ladle of pasta water to pan and toss. Cook for one minute. Season with pepper.
Transfer to serving dishes. Top with remaining crispy sage and prosciutto. Garnish with lemon zest and Parmesan.