Grease the baking pan with oil and sprinkle cocoa powder in it.
Preheat oven at 180 degrees.
In a deep bowl, add oil and sugar and whisk it well till sugar is dissolved. Add vanilla extract or essence.
In another bowl, add flour, cocoa powder, salt, baking soda and mix well with the help of a spoon or spatula.
Now add these dry ingredients into the wet ingredients and mix with the help of spoon/whisk. The mix will be dry.
Fold in grated bottlegourd or lauki to the batter as well as choco chips or walnuts and cover the bowl and keep aside for 5 minutes.
Check after 5 minutes , the vegetable must have moistened the batter which would now look moist. If it still looks dry. keep aside for another 5 minutes. Add caramel or chocolate sauce if desired or can add 1 tbsp water or milk for required consistency. This addition is optional.
Pour the batter in greased tin and level the batter with the help of spatula. Sprinkle some choco chips on the top.
Bake in a preheated oven at 180 degrees for around 35 minutes.
Demould and keep it on a wire rack till cool or you can cut into pieces and enjoy when it is still warm.
This tastes best after a few hours or next day as flavours get more settled .