Mix flour, sugar and ground almonds in a large bowl.
With fingers, work in butter and vanilla until the mixture no longer sticks to the sides of the bowl.
Chill the dough for about 1 hour.
Preheat the oven to 350F.
Taking about 1 Tbsp of the cookie dough (or the size you wish), form dough into a log and shape into a crescent moon (thicker in the middle and forming slightly-rounded points on the ends).
Press the tops of the crescents into the chopped sliced almonds.
Bake for about 10 minutes or until lightly browned.
Cool on pan for about 10 minutes.
While the cookies are still warm, roll them in the fruit sugar until coated.
Important: The cookies are very fragile while warm so I usually put the fruit sugar into a bowl, place the cookie on top of the sugar and then use a spoon to generously sprinkle the cookie with sugar. Tap off excess sugar.