How to make
Mix the grated pumpkin along with the sugar and leave the mixture for 10 minutes (juice is released, but don't worry about that).
Grind the walnuts in a blender, but not very finely.
Sift the flour along with the baking powder.
To the pumpkin add the oil, the soda dissolved in warm water, the walnuts and the cinnamon. Mix well with a spatula or a wooden spoon.
Gradually add the flour, by stirring well, so that no lumps form.
Pour the mixture into a greased and floured mold.
Bake the pumpkin sponge cake in a non preheated oven at 360°F (180°C) for about an hour and a half and to make sure it's fully baked, check it with a stick.