Step by step

Combine in a bowl the cooked meat mixture, half an egg, the grated zest of one lemon, Parmesan, coarsely chopped parsley, nutmeg, salt and pepper.

Be very careful how you slit open the olives: do it so that the cut does not allow the filling to leak out, nor end up with an olive cut in half.
Latin authors such as Marziale and Catone cited the special varieties of olives that were used to prepare this delicacy.