Boil water in a pot. Add oil and salt. Pour the flour sifting it and mix vigorously until the dough is homogeneous. Put it in a bowl and add the eggs one at a time. Turn on the oven (conventional) at 220 degrees.
On a baking tray covered with baking paper, place (4 cm spaced out) cream puffs pressing on the pastry bag with a star-shaped tip. Bake for approximately 15-20 minutes and when the cream puffs are golden and puffy, continue cooking for another 20 minutes leaving the oven semi-open.
For the filling, pour the cream into a saucepan. Put it on the fire (low heat). Meanwhile, in a mortar, crush the white pepper grains and add the powders to the cream. Mix the cream, then add the grated zests of two lemons and the Parmigiano Reggiano, remembering that you should never change direction. Proceed until the cream is thick and becomes firm (to help yourself and be faster, add to the dough 1 teaspoon cornflour when you add the other ingredients to the cream). Leave it to cool. Stuff the cream puffs with a tablespoon of cream and a slice of Parma Ham.