1. Start with the Mirabelle plums – they will take the longest to prepare. Wash and dry them, then cut them in half and remove the stones. Set them aside until needed.

2. Add the cornstarch, sugar, and vanilla extract for the custard to a small bowl and mix with a little milk until well combined. Pour the remaining milk into a saucepan and bring to a boil. As soon as you can see bubbles starting to rise, add the cornstarch mixture and stir it in. Let the custard cook for a moment (while stirring constantly) until it has thickened nicely. Remove the saucepan from the heat and let the custard cool for about 5 minutes, then add the egg yolk and stir it in. Set aside until ready to use – stirring occasionally to prevent a skin from forming.

3. Preheat the oven to 180°C (350°F) fan-forced. Line a 24cm springform tin* with baking parchment and set aside.

4. For the streusels, add flour, sugar, ground almonds, and salt to a large bowl. Add the butter in small pieces. Next, add the egg and vanilla extract and mix them in. We always use a fork first until the egg is reasonably well combined with the flour – then we use our hands to create different-sized streusels.

5. Transfer about 2/3 of the streusels to the prepared springform tin and press them to the bottom and sides – you want the dough going at least two fingers wide up the sides. Next, pour the custard into the baking tin and distribute evenly. Add the Mirabelle plums on top. Mix the remaining streusels with the sliced almonds and sprinkle everything on top of the plums. Sprinkle some additional coarse sugar on top (optional) and bake the cake for about 35-38 minutes in the lower third of the preheated oven. The Mirabelle plums should have softened, and the streusel should look golden. If the streusels get too dark, simply cover the cake with a piece of baking parchment and continue baking. Remove the finished cake from the oven and let it cool down completely on a wire rack. Serve with whipped cream.