On a work surface, combine flour with 1/2 cup of sugar and make a well.
Add 1 egg yolk, a pinch of salt and pats of butter at room temperature.
Knead until the dough is soft and smooth. Shape into a ball, cover with a cotton towel and set aside to rest in a cool place for about 1 hour.
Strain ricotta through a sieve. In a bowl, combine ricotta, Caciotta cheese, mozzarella and diced prosciutto. Mix well and add 1 1/2 tablespoons sugar, grated Pecorino cheese, one whole egg and one yolk. Combine everything.
Divide dough into two pieces, one slightly larger than the other. Flatten and roll out with a rolling pin into two 1/8-inch discs.
Oil a pie pan and line with the bigger disc, letting any excess dough hang out the sides.
Spoon in filling, levelling with a spatula. Cover with the smaller disc and seal pie by folding in the overhang of the larger shell.
Beat one egg with a small amount of water and brush surface to seal and give it a nice golden color.