Put the bran cereal and milk in a large mixing bowl and stir just to mix. Leave to soak for 15 minutes. Meanwhile, preheat the oven to 220C/425F/Gas 7. Line a 12-hole muffin tray with paper muffin cases.
Add half the zest to the cereal and milk and put to one side. In a small bowl, add the cream cheese and caster sugar to the remaining zest and mix well – this will be your filling.
Using the coarse-hole side of a grater, grate the carrots onto a board. Weigh out 150g/5½oz grated carrot and add to the large bowl. (Save any leftover carrots for a salad.)
By now the cereal will be very mushy. Add the brown sugar and mix well with a wooden spoon. Sift in the flour, baking powder, cinnamon and ginger but don’t mix them in just yet.
Break the eggs into another bowl and add the oil. Beat with a fork just until the egg yolks are broken up and mixed with the whites. Tip into the large bowl and mix everything together with the wooden spoon.
Using a medium-sized spoon, drop a dollop of the carrot mixture into each paper muffin case in the tray. Drop a small spoonful of the cream cheese filling into the middle.
Cover the filling with the rest of the carrot mixture, dividing it evenly among the cases. Place in the heated oven and bake for about 20 minutes until golden-brown. Check the muffins are cooked by gently pressing the centre of a muffin with your finger – if it springs back then it’s ready.
Remove the tray from the oven and leave for five minutes, then carefully transfer the muffins to a wire rack to cool. Store in an airtight container and eat within 24 hours.