Preheat the oven to 325 degrees F. In the bowl of a mixer, cream the butter and sugar.
2
In a separate bowl, stir together the ground hazelnuts, flour, and chocolate. Stir into the butter mixture.
3
In another bowl, pour the coffee powder and water, stirring until the powder is dissolved. Stir into the butter mixture.
4
Scoop up about 2 teaspoons of the cookie dough and shape into a ball. Place on a cookie sheet. Repeat until there is an entire tray of balls. Press a whole hazelnut into the top of each ball.
5
Bake about 15 minutes, or until golden. Allow the cookies to cool on the cookie sheet for 1 minute, then remove to a wire rack to cool completely.
6
In a clean bowl, stir together the powdered sugar and cocoa and sift it over the cookies, if desired.