Grease baking pan with oil and preheat oven to 180 degree celsius
Add wheat flour ,cocoa powder ,salt,baking powder and baking soda in bowl,walnuts,salt
In another bowl add sugar and hot water to dissolve it
Add butter in sugar syrup
Add vanilla essence in sugar syrup
Now add wet mixture with dry mixture
Now it's time to add the mayonnaise because of its oily nature it nourishes the whole batter and give it a twist and make it more softer
There should be no lumps in batter.
Pour the batter in pan and bake it for 10 min
Decorate it according to ur will and availability.