Cream butter with sugar and egg yolks. Fold in flour and baking powder. Beat egg whites until stiff and fold into flour mixture. Pour into a large, greased and floured tart pan and bake at 180° for about 30 minutes.
Let cool and spread with strawberry jam.
Preparation Filling: Finely grind the poppy seeds. Bring the milk and sugar to the boil, add the poppy seeds, breadcrumbs, lemon zest and vanilla sugar and simmer at reduced heat for about 30 minutes.
Let cool and spread on the tart base.
Pastry lid preparation:
Beat egg yolks with sugar until foamy. Beat egg whites until stiff. Continue beating in a water bath, adding flour and melted butter in portions. Pour over the poppy seeds and bake at 170 degrees for about 25 minutes until golden. Garnish with powdered sugar.