Tip the flour into a bowl and add the baking powder. Measure the milk into a jug and stir in the butternut squash, followed by the egg yolk.
Make a well in the centre of the flour and gradually add the milk mixture until you have a lump-free batter. Alternatively, tip everything into a blender and whizz it.
Whisk the egg white until stiff, then fold it into the batter.
Heat a non-stick pan and cook 1 large or 3 small pancakes at a time (if making small pancakes, use 1 tbsp for each). Wait until lots of bubbles have risen to the top and the surface has begun to dry out before turning them over, but keep an eye on the base to make sure it doesn’t get too brown. Repeat with the remaining mixture.