Preheat oven to 350ºF. Toast hazelnuts on a baking sheet for 8 minutes or until lightly browned. Let cool. Finely grind in a food processor, pulsing so as not to make into a paste. Set aside.
Sift together baking powder, cinnamon, and flour, set aside. Place softened butter and sugar in a large bowl, beat with an electric mixer until light and fluffy. In a separate bowl, whisk egg and vanilla extract together. Add slowly to butter and sugar mixture. Blend until just incorporated. Fold in the ground hazelnuts and mix until a soft dough forms. Divide dough in half. Cover with cellophane and chill covered for 2 hours, or overnight.
Preheat oven to 350ºF.
In a large bowl, gently mix together the jam, cranberries, raspberries, flour, sugar, and lemon juice.
Take one dough out of refrigerator and roll out to 10 x ¼” circle, place into the bottom of a 9” tart ring with a removable bottom. The dough should go even with the edge of the tart pan, cut off any over hang. Brush lightly with egg glaze. Spread the filling into the shell. Remove remaining dough from refrigerator. Roll out to ¼: thickness, and cut into 1/2” strips. Starting with a corner, place strip ½” apart, diagonally across tart, Repeat with the strips going the other way. Brush with egg glaze. With the remaining dough, roll a piece into a rope that is ½” in diameter and long enough to fit around the edge of the tart on top of the strips. With a fork make an impression on the edge all around the tart. Bake for 25 minutes, or until the dough is golden brown and the filling is bubbly.