(The recipe is adapted from here.)
For the dough:
3 cups + 1/4 cup flour
about 1 cup milk
1/4 cup + 1/2 tablespoon sugar
about 1/3 cup melted butter
1 tablespoon dry yeast
1/4 teaspoon salt
Do what you always do when making yeast dough. I mix the yeast with sugar and salt, add the flour, then milk, egg and butter. Combine those ingredients and knead your dough thoroughly until it’s smooth. Then, put it in a bowl and cover it. Let it rise for 1 or 2 hours, punch it down twice in between.
For the filling:
1 cup + 1/2 cup ground poppy seeds
1 cup milk
1/3 cup chocolate custard powder
1/2 cup sugar
1/2 teaspoon cinnamon
a splash of amaretto or other liqueur or rum
Stir all those ingredients in a pot and let it boil up for a minute. Put it away from the heat.
While the filling cools, you can roll out your dough. But before, turn on your oven and preheat it to 160° C or 320° F with circulating heat.
Then, distribute your yummy black filling on the dough. Spread it evenly.
After that, I think you know what to do. Roll your strudel.
If you have quite big holes afterwards, take some dough from the ends and try to fill them a bit. Stick those pieces on with 1 whipped egg with which you brush your whole strudel.
Put it in the oven and leave it there for about 20-25 minutes until it’s golden brown.
Let it cool, cut it in slices and enjoy!