Streusel Cake with Poppy Seed Filling (Mohn-Streuselkuchen)

Combine milk and granulated sugar in a medium saucepan over medium heat and bring to a simmer. Slowly add semolina, whisking continuously. Reduce heat to low, continue to stir with a wooden spoon, and simmer for 4 to 6 minutes, until thickened. Add poppy seeds and vanilla sugar and mix thoroughly. Stir in egg, a little at a time, mixing vigorously the entire time. Remove from heat and stir in salt and raisins. Let cool to room temperature. (Filling can be stored, covered, in the refrigerator for up to 6 days, until needed.)

Reserve 1/2 cup and transfer remaining dough to the prepared pan, gently pressing mixture onto the bottom and up the sides of the pan in an even layer. Add the poppy seed filling and spread it evenly on top. Sprinkle remaining streusel over the top evenly.

In a medium bowl, whip heavy cream by hand or using a mixer. Add vanilla sugar and whip just until combined. Serve cake with the whipped cream.

To make your own vanilla sugar, split a vanilla bean in half lengthwise and place in a container of sugar. Set aside for at least 5 days to infuse. When the container gets low, just replenish with more sugar, as the vanilla bean will impart its flavor and fragrance for months.