Layered Poppy Seed Pastries

In a small bowl, combine warm milk, sugar, and yeast. Stir until the yeast is fully dissolved. Set the mixture aside.

1. In the bowl of an electric mixer, blend the flour, baking powder, salt, and lemon zest. | 2. Add the butter and mix until the dough becomes crumbly. | 3. In a separate small bowl, beat the egg, egg yolk, and vanilla. Gradually add the egg mixture to the flour mixture, alternating with the milk-yeast mixture. Mix until the dough comes together.

1. Transfer the dough to a floured surface. Divide it into 4 equal parts. | 2. Knead each part into a flat disc, then wrap each disc in plastic wrap and refrigerate for 1 hour.

1. Spoon the poppy seed filling into a pastry bag. Set aside. | 2. In a small bowl, blend sugar and chopped walnuts for the filling.

1. Roll each disc of dough into a thin sheet large enough to fit into a 13x9-inch baking dish. Trim each sheet to fit the dish, reserving the trimmings for a Poppy Seed Strudel if desired. | 2. Place the first sheet of dough in the bottom of the prepared baking dish. | 3. Pipe half of the poppy seed filling onto the dough (or spread it with a spoon). Spread the filling evenly. | 4. Place the second sheet of dough on top, then sprinkle with 1 cup of walnut-sugar mixture. | 5. Add a third sheet of dough, followed by the remaining poppy seed filling, and top with the final sheet of dough.

Cover the baking dish with a kitchen towel and let the pastry rest for 30 minutes.

1. Preheat your oven to 350°F (175°C). | 2. Brush the top layer of dough with the egg yolk mixture. | 3. Bake for 45 minutes, or until the pastry is golden brown.

1. While hot, cut the pastry into 24 squares. Allow to cool in the pan. | 2. If freezing, wrap each pastry square in plastic wrap, then foil, and store in resealable plastic bags in the freezer.