In a medium bowl, whisk together flour, sugar, baking powder, salt, and cinnamon.

In a food processor fitted with the S blade, pulse the hazelnuts with 1/4 cup of the flour mixture until they’re finely ground.

Add the remaining flour mixture and process to combine. Add butter or margarine and pulse until the mixture resembles coarse crumbs. Add the egg yolks and vanilla and pulse until the dough just comes together.

Form the dough into two discs. Wrap in plastic and refrigerate for 30 minutes.

Preheat oven to 350 degrees Fahrenheit (180 degrees Celsius).

Roll out one disc at a time. Lightly dust some Gefen Parchment Paper with flour and place the dough on top of it. Place another piece of parchment paper over that and roll it between the two pieces of paper to about 1/8 inch (1/2 centimeter) thick.

At this point you can either cut it into squares or use a cookie cutter for any desired shape. If the dough is still soft, place the rolled dough between the parchment sheets into the fridge for about a half hour and then try again.

Place cookies onto a lined baking sheet and bake until the edges just begin to brown, about 10–12 minutes.

Scoop some vanilla ice cream into a dessert bowl. Top with fresh or canned passion fruit and stick a flower cookie on top.