Ground hazelnuts until it reaches a flour like consistency. Be careful not to over process! Cream together butter and sugar for 2 minutes. Add the egg and vanilla. Continue to mix for an additional minute. Combine flour, ground hazelnuts and Italian baking powder in one bowl and gradually add to mixer. You should have a large soft ball of dough. Wrap dough in clear wrap and refrigerate for at least one hour.

Pre heat oven to 325 degrees f. Take a small piece of dough and roll into a ball. Place on a parchment lined baking sheet. Repeat until no more dough. Bake in oven for aprox. 20 mins. Rotate pans in oven halfway through. Remove when slightly golden and cool on racks.

Melt chocolate. Dollop a small spoonfull of chocolate into center of cookie, flat side up and then top with another cookie flat side down to form a sandwich. When all the cookies have been sandwiched together with chocolate. Drizzle tops of each cookie with reaminng chocolate. Refrierate to set.