Sift together 11/2 cups of plain flour & 1 tsp of baking soda. Grease an 8″ cake tin & keep aside. Preheat the oven to 180C.
Beat together 1 cup of cold buttermilk, 3 heaping tbsps of unsweetened cocoa powder, 1 tbsp of white vinegar & 5 tbsps of canola oil; add 1 cup of caster sugar to this little by little & beat well with your mixer till well combined. Add 1 tsp of vanilla essence & 1/2 tsp of salt & mix.
Fold in the sifted flour mixture & transfer the batter to the greased baking pan. Bake at 180C for 30-35 minutes.
Let cool for 10 minutes before inverting the cake on to a rack to cool completely.
Serve with chocolate sauce.
For the chocolate sauce combine 4 tbsps of unsweetened cocoa powder, 4 tbsps of granulated sugar, 4 tbsps of water & 1 tsp of butter. Cook in your microwave on high power for a minute.