Wash, peel and grate the butternut squash on a coarse grater, salt it and leave it to sit about 30 min.
Put the butter and sugar in a bowl, stir well, then add the eggs and milk, stir well and gradually add the flour, the cinnamon at the end. Once you've beaten the mixture well, add the pumpkin.
Pour the resulting mixture into a pre-greased tray. Bake in a preheated oven until ready.
Once ready, sprinkle cake with powdered sugar.