1. Start with the vanilla sauce by taking about 1/4 cup (60ml) of the milk to the side for later. Add the milk together with the sugar and salt to a saucepan. Slit the vanilla bean pod lengthwise and remove the seeds. Add both to the milk and warm up. Let the vanilla soak in the warm milk for about 10 minutes – the milk should be warm, not hot or boiling.

2. Mix the milk you kept on the side with the cornstarch and egg yolk. Heat up the milk until it starts boiling, remove the vanilla bean pod, then add the cornstarch mixture while stirring constantly until the sauce starts to thicken and bubble. Remove from the heat and let cool down while stirring occasionally to prevent the sauce from getting a skin.

3. Preheat the oven to 180°C (350°F). Grease a 24cm springform tin* or tart tin and sprinkle it with some breadcrumbs. Set aside.

4. Add the butter and sugar for the cake batter to a large bowl and mix until light and fluffy. Add the eggs one by one and mix well after each addition. Mix in the vanilla extract as well. Combine the flour with baking powder, salt and lemon zest and add it together with the milk to the bowl and mix until just combined – do not overmix. Transfer the batter to the prepared baking tin, smooth out the top and set it aside.

5. Peel the apples, cut them in half lengthwise and remove the cores (works fine with a teaspoon). Cut the apple halves on the rounded sides fan-like so you have thin slices that are still connected at the bottom. Place these apple halves on top of the batter, the cut slices facing up and press them a bit down.

6. Bake the cake for about 40-45 minutes – check after about 30 minutes or so and cover it with aluminum foil, if necessary. The cake should not get too dark. Bake the cake until a toothpick inserted in the center comes out clean. Take it out of the oven and let it cool down on a wire rack completely. Dust the cake with confectioners‘ sugar to your liking and serve it with the vanilla sauce.