Preheat the oven to 190°C/Fan 170°C/Gas 5 and grease the inside of a bundt tin well.
Put the oil, sugar, eggs and carrot in a bowl and mix well.
Add the flour and baking powder, salt, cinnamon, mixed spice and nutmeg to a separate bowl and mix till incorporated. Add to the wet ingredients and mix till you have an even batter.
Make the cream cheese ripple by whisking the cream cheese, butter, icing sugar, milk and vanilla bean extract together till combined.
Pour half the carrot cake batter into the tin and level off. Add the cream cheese on top, then add the rest of the carrot cake batter in a final layer. Use a skewer to ripple the batter.
Bake for 50 minutes to 1 hour until the cake is risen and firm and a skewer inserted into the middle comes out clean.
Take out and leave to cool in the tin for at least 20 minutes so that the cake is firm enough to turn out.
Use a table knife or small palette knife to gently loosen the edges of the cake, then turn out. Once cooled, dust with icing sugar and serve. Will keep in the fridge for up to 5 days.