Heat oven to 350 degrees. Break chocolate into small pieces. In the bowl of a food procesor, combine chocolate, sugar and almonds and pulse until finely ground, about 45 seconds.
Add flour, cinnamon, and salt, pulsing 3 or 4 times to combine. Add butter, pulsing until mixture resembles coarse meal. Transfer to a bowl.
In a small bowl, combine egg and lemon juice. Add to flour mixture, stirring with a fork until mixture comes together.
Place an 8-inch springform pan or bottomless tart ring on a parchment lined baking sheet. Press about two-thirds of the dough into the ring, forming a 1/2 inch thick crust. Crust should be thicker on the edges, coming to a height of 1 inch on the ring.
Using a rubber spatula, spread jam evenly over bottom of crust.
Divide remaining dough into quarters. Flour work surface and hands well, and roll dough into long thin ropes about 1/3 inch in diameter. Arrange decoratively along top of tart, pressing gently to slightly flatten ropes.
Bake tart until golden brown around the edges, about 50 minutes. Let cool to room temperature. Chill and dust lightly with confectioner's sugar before serving.