Place egg and flour in a bowl and mix with a fork until it resembles bread crumbs. At this point use your hands to bring the mixture together to form a dough.
Place the dough on a lightly floured work service and kneed until shiny. Cover with plastic wrap and let rest for about 1/2 hour.
While the dough is resting, make your filling by mixing together the ricotta, lemon zest, nutmeg, mint and Parmesan - you may want to reserve a little Parmesan and mint for serving - and then carefully season to balance the flavours. Squeeze a little lemon juice into the mix to loosen it a bit. If you're partial to a little bit more Parmesan, mint or lemon, then do personalize the dish to your liking. Roll good teaspoons of the mix into little balls ready to fill your caramella.
Run dough through pasta machine on its thickest setting a until it is smooth and shiny.
Reduce setting each time until the pasta is roughly as thick as a beer mat.
Cut the pasta into 10 (4 by 2 1/2-inch) rectangles. Fill the middle with the little balls of filling and brush lightly with water. Roll up. Keep on a flour-dusted baking sheet in the refrigerator until you need them, and try to cook them as fresh as possible.
Make as many as you can, but I like to serve about 4 per person.
To serve, place the caramella in boiling salted water for 3 to 4 minutes, then drain, reserving some of the cooking water. Melt 3 good knobs of butter in a non-stick pan with the juice of 1/2 a lemon and a couple of tablespoons of the reserved cooking water. Season a little, and toss the pasta in this flavoured butter. Serve straight away with a little extra Parmesan and mint scattered over the top.