Preheat oven to 180 degrees C. Grease and flour a 25cm ring tin.
In a large bowl sift and mix together the flour, baking powder, bicarbonate of soda, salt and cinnamon. Make a well in the centre and pour in the eggs, sugar, oil, applesauce and vanilla. Mix well and pour into prepared ring tin.
Bake in the preheated oven for 50 to 60 minutes or until a toothpick inserted into the centre of the cake comes out clean. Let cool in tin for 10 minutes then turn out onto a cake rack and cool completely. Dust with icing sugar if desired.