Bavarian Plum Sheet Cake

Combine flour and baking powder in a large mixing container. Mingle these dry ingredients thoroughly. Next, incorporate 1 cup sugar, vanilla sugar, and salt into the mixture. Introduce 1 1/3 cups of softened butter and eggs to the blend, stirring until everything is well combined. Work the ingredients together into a cohesive dough. Form this dough into a spherical shape, flatten it slightly, cover it with plastic wrap, and refrigerate for at least 1 hour or up to overnight.

Heat your oven to 350 degrees F (175 degrees C). Apply a thin layer of butter to a baking sheet to prevent the pastry from sticking. Slice plums in half once more, but not all the way through, allowing them to fan out naturally.

Unfold and roll out the chilled pastry dough on a lightly dusted surface. Cover the bottom and sides of the prepared baking sheet with the dough, ensuring a snug fit. In a small bowl, combine 2 tablespoons of sugar and cinnamon to create a sweet spice blend.

Arrange the halved plums side by side on the pastry dough, allowing smaller plums to overlap slightly. Dot each plum with 2 tablespoons of softened butter and sprinkle with cinnamon sugar and almonds.

Place the baking sheet in the preheated oven and bake until the pastry crust is lightly golden brown, 30 to 40 minutes. Remove from the oven and allow the plum cake to cool before cutting it into squares. Serve warm or at room temperature.