Pre-heat the oven to 160°C (320°F). Prepare a mini bundt tin or place individual silicone moulds on a baking tray.
Cream the butter and sugar together until smooth. Beat the eggs into the mixture one at a time and then add the lemon juice.
In a separate bowl, mix the baking powder, flour, salt and vanilla sugar until well combined. Gradually add to the butter mixture a bit at a time, alternating with the milk, until the batter is smooth.
Pour into the tins/moulds and gently push 3 or 4 berries into the batter of each cake, covering over the top so the berries can't be seen. Bake for around 18-23 minutes. The cakes are ready when an inserted skewer comes out clean.
Leave to cool completely and then turn out onto a wire rack. Sprinkle with icing sugar and then serve. Enjoy!