Preheat oven to 180° C.

Grease a square cake tin and lightly dust with dry flour. Place a sieve over a bowl and put refined flour, cornstarch, baking soda, salt, cinnamon powder, cocoa powder and sift. Mix well.

Add castor sugar and mix. Add 1 cup chilled water and mix. Add vanilla essence and mix well with a hand blender. Add vinegar and blend some more. Pour the batter into the prepared tin and bake in the preheated oven for 35-40 minutes. When done, take the tin out and let the cake cool completely.

For the frosting mix icing sugar, cinnamon powder, cocoa powder, honey and 2 tbsps water in a bowl and mix well. Heat oil in a non stick pan, add the icing sugar mixture and cook on medium heat till sugar melts completely. Cool it.

Place the cake over foil and trim the sides of the cake. Pour the frosting over the cake and let it slide over the sides. If you like you can level the frosting over the sides with a palate knife.

Keep in the refrigerator to set.

Cut into slices and serve.