2. Cut the Rhubarb into chunks and stew in a small pot with about a third of a cup of water, until quite soft.
3. Finely grate the nutmeg (enough for 2 teaspoons) and sift flour, baking powder, bicarb of soda and nutmeg into the large mixing bowl.
4. Peel and coarsely grate the carrots and apples.
5. Combine eggs and vegetable oil in the small bowl and whisk lightly.
6.Add brown sugar, rhubarb, grated carrot and apple to the flour mixture, then add eggs and oil mixture and stir with a wooden spoon until just combined.
7. Spoon equal amounts of mixture into your baking tin and bake in the oven for 35 minutes.
8. While the cake is cooking, cut the rind from your oranges (with as little of the bitter white ‘pith’ as possible). Add the rind, cream cheese, icing sugar and vanilla extract to the bowl of the food processor and blend until smooth. Keep in the fridge until your cake is ready.
9. Check whether the cake is ready by inserting a skewer into the middle of the cake, if it comes out clean the cake is ready.
10. Cool the cake in the tin on a wire rack for 10 minutes and then turn out onto the wire rack.
Use the spatula to spread the icing onto your cake.