Apple, Walnut, and Poppy Seed Bars

Flodni are tall, triple-layer bars—a hearty, delicious snack created by the Jews of Hungary. The same dough and fillings can be rolled into cylinder shapes, in which case they are called kindli. To keep the kitchen kosher, many Jewish cooks didn’t cook with butter (even though it was allowed under some circumstances), substituting chicken or goose fat (schmalz) in many of their doughs. My version isn’t kosher, but it uses vegetable shortening, which gives the crust the crumbly textur