I love how these cookies look and taste, which is good because these are by far the most time consuming and work of all the cookies I make. They are absolutely wonderful though and the perfect cookie to have with coffee. One of the keys to these is to be sure to find a nice thick raspberry preserves. I actually bought a couple of jars of raspberry preserves just to be sure I found one that wasn't too thin and runny (you don't want jelly because it will run right off the cookie). This is another cookie you need to refrigerate at least 2 hours before baking. Because these are double layer cookies, this recipe yields only about 2 dozen cookies at the most.
2/3 c hazelnuts
1/2 c packed brown sugar
2 1/2 c flour
1/2 t baking powder
1/2 t salt
1/4 t cinnamon
1 c unsalted butter, at room temperature
1 large egg
1 t vanilla
raspberry (or strawberry) preserves
Toast the hazelnuts in shallow pan in preheated 350 degree oven for 10 minutes or until fragrant and skins begin to loosen. Rub hazelnuts in kitchen towel to remove any loose skins. Cool to room temperature. Pulse nuts and 1/4 c brown sugar in food processor until nuts are finely ground. In a separate bowl, whisk together flour, baking powder, salt and cinnamon. Beat together butter and remaining 1/4 c brown sugar in a large bowl at medium high speed in a blender until light and fluffy, about 3 minutes. Add nut mixture and beat until combined, about 1 minute. Beat in egg and vanilla. Reduce speed to low and add flour mixture, mixing until just combined.
With floured hands, form dough into 2 balls and flatten each into a 5-inch disk. Chill disks wrapped in plastic wrap until firm, at least 2 hours.
Roll out 1 disk of dough into an 11 inch round (1/8" thick) between 2 sheets of wax paper (keep remaining dough chilled). If dough becomes too soft to roll out, rewrap in plastic and chill until firm. Cut out as many cookies as possible from dough with a larger cookie cutter and transfer to ungreased baking sheet. Using smaller cookie cutter, cut out the centers from half of the cookies (this is easier to do once they are on the baking sheet), reserving centers and rerolling along with scraps. Bake cookies, switching position of sheets halfway through baking in a preheated 350 degrees oven until edges are golden, about 8 - 1 0 minutes total. Then transfer to cool completely on a baking rack (baking time depends on thickness of cookies. Try for uniform thickness of all cookies for the most even baking). Repeat the process until all the dough is used (cooling off dough in the freezer as necessary).
To assemble cookies, spread preserves on flat side of 1 cookie and sandwich jam with flat side of 1 windowed cookie. Sprinkle with confectioner's sugar.