Pre-heat oven to 160ºC.
Sieve the flour and baking powder into a mixing bowl, then make a well in the centre.
In a jug, whisk together the milk, eggs, rapeseed oil, maple syrup and cinnamon.
Slowly pour the wet mixture into the flour whisking from the middle outwards which prevents lumps. Keep whisking until it is fully combined and has turned into a silky batter.
Grate in the courgettes, then place into a clean tea towel and squeeze some of their juice out. Add to the batter along with the grated apples, carrots and rains and stir well.
Spoon into a mini muffin tin lightly oiled, then bake for 30 minutes until a skewer comes out clean.
Cool fully before serving.