1) Preheat the oven to 375°F. If you're making shaped cookies using a cookie press, chill two ungreased baking sheets in the freezer while you make the dough.
2) Beat together the butter, sugar, cream cheese, salt, vanilla, Fiori di Sicilia, and zest.
3) Beat in the egg yolk, then stir in the flour.
4) If you're using a cookie press, follow the directions that come with the press to pipe cookies onto the chilled baking sheets.
5) If you're not using a cookie press, simply drop the dough by the teaspoonful onto the ungreased baking sheets. Top with coarse white sparkling sugar or colored sugar, if desired.
6) Bake the cookies for 8 to 10 minutes, until they're brown around the edges.
7) Remove from the oven, and wait 5 minutes before transferring the cookies to racks to cool. Be sure to move the cookies before they're totally cool, as otherwise they may stick to the baking sheet.
8) Store completely cool cookies airtight, at room temperature, for up to a week; freeze for longer storage.
Yield: 7 to 8 dozen cookies.