Preheat oven to 180°C (350°F) and grease a 26 cm springform pan.

Cream butter and sugar until light and fluffy. Add vanilla and beat in eggs one at a time.

Mix in baking powder and salt, then gently fold in flour until combined.

Spread batter evenly into the prepared pan.

Wash, halve, and pit the plums. Arrange them cut-side down in the batter.

In a bowl, mix flour, almonds, cinnamon, sugar, and salt. Add melted butter and mix into crumbly streusel.

Sprinkle streusel evenly over the plums.

Bake for 40–45 minutes until golden and cooked through.

Cool slightly, then remove from pan and allow to cool completely before serving.

This German Plum Streusel Cake is best enjoyed slightly warm or at room temperature.