How to Make It
Preheat the oven to 375° and lightly spray a 9-inch fluted tart pan with a removable bottom with vegetable cooking spray. In a food processor, pulse the hazelnuts until finely ground. Add the 1 cup of flour and the sugar, cocoa, cinnamon and cloves and pulse to blend. Add the butter and egg yolk and pulse until a soft dough forms. Turn the dough out onto a lightly floured surface and knead 2 or 3 times.
Press two-thirds of the dough into the tart pan in an even layer, pressing it into the corners. Spread the jam in the crust. On a lightly floured surface, roll out the remaining dough 1/4 inch thick. Using lightly floured small, decorative cookie cutters, stamp out as many shapes as possible and arrange them on the jam. Bake in the lower third of the oven for about 45 minutes, until the crust is deep brown and the jam is bubbling. Let cool, then serve.
Hazelnut flour, which is simply ground hazelnuts, is available at health food stores and from kingarthurflour.com.