Makes: 24 filled trees. prep: 25 minutes. Refrigerate: overnight. Bake: at 350 degrees for 11 minutes.
In a large bowl, whisk flour, hazelnuts and salt. Set aside
In a large bowl, beat butter and confectioners sugar until smooth, about 3 minutes. Beat in eggs and vanilla. Mixture may look curdled. On low speed, beat in flour mixture. Form dough into a thick disk. Wrap in plastic; refrigerate overnight.
Heat oven to 350°F Coat 2 baking sheets with nonstick cooking spray. Working with a quarter of the dough at a time, roll out on a floured surface 3/16 inch thick. Using a 3-inch Christmas tree cutter, cut out cookies and place on prepared baking sheets. Using a small diamond-shaped cutter, cut out the centers of half the cookies. Reroll scraps if necessary and repeat with remaining dough for a total of 48 cookies.
Bake at 350°F for 11 minutes or until just beginning to turn golden. Remove from baking sheets to wire rack and let cool.
Dust cut-out cookies with confectioners sugar. Puree cherry preserves in food processor; spread 1/2 teaspoon on each remaining cookie. Place cut-out cookies on top of preserve-topped cookies. Let stand at room temperature until set.