Begin by making the poppy seed filling. Using the tip of the knife split the vanilla bean lengthwise and scrape out the vanilla seeds.
Pour 3/4 of the milk in a pot and add sugar and vanilla seeds from the vanilla bean and let cook. Add cornstarch (corn flour) to the remaining milk and stir well. Using a hand grater, grate the marzipan. You could also cut marzipan into smaller pieces if you like.
Once the milk starts boiling, add poppy seed to the pot and mix well. Then stir in milk – corn flour mixture. Let the poppy seed mixture cook for about 2 minutes.
Then remove the pot from heat and crack in the egg and mix well. Add grated marzipan, combine well, and let the filling infuse in the fridge while making the crumbles.
Next make the buttery crumbles. Simply add sugar, almonds, butter, and flour to an empty bowl. Using your hands mix all the ingredients together until small crumbles start to form and set aside as well.
Preheat the oven to 170 °C (338 °F), with both top and bottom heat. Then take the poppy seed filling out of the fridge and mix it very well.
To make the yogurt dough simply combine all the ingredients for the dough in a large mixing bowl and knead for about 1 to maximum 2 minutes. You don’t want to over knead the dough!
Transfer the dough to a lightly floured surface and knead for another minute.
When rolling out this dough, I like to roll it out on a parchment paper, just to make my life easier. Because this no yeast dough, becomes stickier, the longer it sits. To roll out the dough simply put the dough on a parchment paper that’slightly dusted with flour. Slightly flour the dough as well and then roll it outwith a lightly floured rolling pin into a rectangle. About 30 x 40 cm(approximately 11.8 x 15.7 inches)). Spread the poppy seed filling over the rolled-out dough, leaving 1 cm (0.4 inch) free and then roll it up. First roll up about 3 cm (1.18 inch) of the dough on both short sides. Then carefully roll up the dough lengthwise, with the help of the parchment paper. Gently lift up the roll with the help of the parchment paper and put it on a baking sheet lined with parchment paper.
Lightly brush the roll with water and sprinkle the top with crumbles. Using your hands gently press the crumbles on top of the roll, so that they won't slide off. Then bake for about 50 minutes or until nicely golden brown. Before serving drizzle the poppy seed strudel with powdered sugar and lemon glaze. Enjoy!