Prepare the yeast dough: In a large bowl, mix 3 cups of flour, ¼ cup sugar, ½ cup of butter, and salt. Dissolve yeast in lukewarm milk and let it rest for 5 minutes. Add milk mixture, eggs, and vanilla extract to the flour mixture. Combine until a soft dough forms. Knead until smooth and elastic, about 5-7 minutes. Cover and let it rise in a warm place for about 1 hour, or until doubled in size.
3 cups All-Purpose Flour, ½ cup Granulated Sugar, 1 cup Milk, 1 package Active Dry Yeast, 2 large Eggs, 1 tsp. Vanilla Extract, ½ tsp. Salt, ½ cup Unsalted Butter
Preheat oven to 350°F (175°C). Grease a large baking sheet.
Prepare the streusel topping: In a medium bowl, combine the remaining 1 cup of flour, ½ cup sugar, and cinnamon. Cut in ½ cup of cold butter using a pastry cutter or your fingers until the mixture resembles coarse crumbs.
1 cup All-Purpose Flour, ½ cup Granulated Sugar, ½ cup Unsalted Butter, 1 tsp. Ground Cinnamon
Prepare the plums: Wash, pit, and slice the plums into quarters.
2 lb. Prune Plums
Assemble the cake: Once the dough has risen, punch it down and roll it out on a lightly floured surface into a rectangle approximately the size of your baking sheet. Transfer the dough to the greased baking sheet, pressing it gently into the corners and edges.
Arrange the plum quarters on top of the dough in rows, skin side up, slightly overlapping.
Sprinkle the streusel topping evenly over the plums.
Bake for 35-40 minutes, or until the streusel is golden brown and a toothpick inserted in the center of the cake comes out clean.
Remove from the oven and allow the cake to cool slightly on a wire rack.
Serve warm or at room temperature, with a dusting of powdered sugar or a dollop of whipped cream, if desired. Enjoy your delicious German Plum Cake with Streusel Topping (Zetschgenkuchen)!