Preheat oven to 350 degrees. Spread hazelnuts in a single layer on a rimmed baking sheet; toast, stirring occasionally, until skins begin to split, about 15 minutes. Immediately rub hazelnuts vigorously in a clean kitchen towel to remove skins (as much as will come off easily). Let cool.
In a food processor, pulse hazelnuts and almonds until finely ground. (Be careful not to overprocess; you don't want the mixture to become a paste.) In a medium bowl, whisk together flour, baking powder, cinnamon, salt, and nut mixture; set aside.
In bowl of an electric mixer fitted with the paddle attachment, beat butter and granulated sugar until light and fluffy, about 3 minutes. Add egg yolk and beat 1 minute to combine. With mixer on low speed, add ground nuts and flour mixture all at once.
Divide dough in half. Set a 10-inch fluted tart pan with a removable bottom on a parchment-lined baking sheet. Using your fingers, press 1 dough half into tart pan. Chill until firm, about 30 minutes. Meanwhile, roll remaining dough half between 2 sheets of parchment paper lightly dusted with flour to a 12-inch round; place on a baking sheet and chill until firm, about 30 minutes.
Using an offset spatula, spread jam evenly over chilled dough in tart pan; set aside. Using a fluted pastry wheel, cut 3/4-inch-wide strips from chilled round of dough. Arrange strips on top of jam in a lattice pattern. Freeze until firm, about 30 minutes. Meanwhile, preheat oven to 350 degrees.
Bake, rotating pan halfway through, until torte is golden brown all over, about 40 minutes. Transfer to a wire rack to cool 20 minutes. Remove ring and cool torte completely. Torte can be kept at room temperature, loosely covered in plastic wrap, for up to 3 days. When ready to serve, dust with confectioners' sugar, if using.