Preheat oven to 350 degrees.

Toast hazelnuts in a dry skillet until lightly golden and smell delish. Let cool.

In a food processor, pulse hazelnuts and almonds until finely ground.

In a mixer, beat butter and sugar., about 3 minutes.

Add yolk and beat 1 minute.

On low, add ground nuts, flour, baking powder, cinnamon and salt.

Divide dough in half.

Set a 10-inch fluted tart pan with a removable bottom on a parchment-lined baking sheet.

Press half the dough in the bottom and up sides.

Chill 30 minutes.

Meanwhile, roll other 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.

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. They are delicate and can be difficult to move. A spatula is helpful.

Freeze until firm, about 30 minutes.

Meanwhile, preheat oven to 350 degrees.

Bake about 40 mins. (*Note: check it at 20mins. Mine was done at 20 but my oven was broken so that is probably why! Better to be safe though, so check at 20 and then can continue 20 more if needed.)

Dust with powdered sugar before serving.