Fiori di Sicilia is a delicate flavor that combines notes of vanilla and orange. These cookies look a little like their namesake "flowers of Sicily" in sweet, crunchy form.
Preheat the oven to 375°F. Have two ungreased cookie sheets on hand.
In a large bowl, mix together the butter, sugar, cream cheese, salt, vanilla, Fiori di Sicilia, and zest just until smooth. Beat in the egg yolk, then mix in the flour.
Fill a cookie press 3/4 full with the dough and press the cookies onto the baking sheets. Give the press a quarter turn after squeezing and before lifting it up; this can help the cookies stay in place. Sprinkle with sparkling sugar.
Bake the cookies for 9 to 11 minutes, until light brown around the edges.
Remove the cookies from the oven and cool on the pan on a rack for 5 minutes. Transfer cookies from the pan to the rack to finish cooling completely.
Store cooled cookies, well-wrapped, at room temperature for several days; freeze for longer storage.
