Preheat the oven to 180°C (360°F) (without fan).

Line a 23 cm (9 inch) springform cake pan with baking paper, and grease the sides with butter.

Place the butter and sugar into the bowl of an electric stand mixer.

Cream the butter and sugar using the flat paddle attachment.

Beat in the egg and vanilla seeds.

In a jug, whisk together the milk and crème fraîche (or sour cream).

Measure the flour, baking powder and salt into a bowl.

With the stand mixer on low speed, add a third of the flour mixture to the batter, followed by a third of the milk mixture.

Lightly beat until everything is incorporated.

Repeat steps 8 and 9 until you have a smooth batter.

Pour the batter into the prepared cake tin.

Thinly slice the peaches. I like to cut the peaches into quarters, and then cut each quarter into 4 thin slices, so that I have 16 slices per peach.

Arrange the peach slices on top of the batter in an overlapping, circular pattern.

Sprinkle the raspberries all over the cake.

Sprinkle the vanilla sugar over the fruit.

Bake the cake for about 45 minutes, or until it is lightly golden and a skewer inserted in the centre comes out clean.

Let the cake cool on a wire rack.

Sprinkle with icing sugar (powdered sugar) just before serving.