Preheat oven to 180°C.
Wash Bottle Gourd, peel, cut into cubes and blend into a fine puree. Pour the puree through a sieve.
Mix all wet ingredients Oil, Curd, Vanilla essence, bottle gourd puree in a bowl. Add sugar. Whisk well till sugar dissolves and mixtures becomes fluffy.
Take slightly warm milk into the small cup. Add filtered coffee. Mix well. Add into the wet mixture.
Sift maida, baking powder, baking soda, salt, unsweetened cocoa powder together twice or thrice for any impurities. Keep aside.
Mix dry ingredients slowly into wet mixture. Fold gently.
Grease baking pan with oil. Dust it with flour and spread evenly.
Pour the mixture in a greased pan. Smooth out and lightly tap the pan so that batter is spread evenly and there are no air bubbles.
Bake a cake for 25-30 minutes. Insert a toothpick, it should come out clean. Let the pan sit on a counter for 5 minutes.
Flip the cake and let it cool on wire rack.
For Chocolate Frosting –
Chop Dark chocolate. Add milk, filtered coffee powder and melt it in a double boiler or microwave for 1 minute. If using microwave keep checking after every 10 seconds.
Keep stirring after each cooking interval. Do this till chocolate melts completely and incorporates well with milk.
Transfer a cake into a plate. Coat it with the prepared chocolate milk frosting until it covers completely from all the side. Once finished, transfer a cake into the refrigerator for 30 minutes.
Once the frosting is set, remove and decorate a cake with grated white chocolate. Serve.