I was little hesitant to try this recipe as i am not sure how a cake recipe without egg would taste like.But there is a start to everything.Even though there are no eggs in this recipe the cake is soft and tasty.I am convinced enough to try more cake recipes without eggs.
This recipe is made dairy free too with almond milk but i don't see why not try this recipe with regular milk ,coconut milk ,soymilk or rice milk.I don't think the taste would go any less.The process behind the soft cake depends on the cornstarch present in custard powder,if you don't have custard powder in hand try this recipe with plain cornstarch(not corn meal ) instead of custard powder.Adding flavouring agents like mango,pista or almonds separately will do.
Next time planning to try this recipe with whole wheat flour,lets wait and see the result...
UPDATE:I did tried it in whole wheat flour and it turned out to be even more spongy thats because of a secret ingredient ie, ENO ( fruit salt , unflavoured).I used 1 cup wheat flour , 1/2 cup All purpose flour and !/2 cup Custard.And everything is the same.I would tried it in all wheat flour without using plain flour but i ran out of whole wheat flour but i am guessing the cake would be still fluffier and spongier.
At the end when i am about to put the batter into cake tray i added ENO to the batter and mix fast and poured into pan and put it in oven.You will definitely surprised by how spongy the cake comes to.If you don't have fruit salt which you can easily find in indian stores you can use Bubbly Water for half the amount of milk or even Vinegar Baking soda mixture to give that bubbly form to the batter.But always add them to the batter at teh last moment when you are about to put the batter into the oven.or the fizz may go flat and batter may become lose its air pockets.
Here is the picture of the cake made of whole wheat flour

Ingredients :


All purpose flour - 1 cup
Sugar - 1/2 cup + 1 tbsp
Custard Powder any flavour - 1/2 cup (i used mango flavour in this recipe,Pista flavour will taste like biscotti)
Milk - 1 cup , i used almond milk
Oil - 1/4 cup
Butter - 1/4 cup 
Baking Powder - 2 tsp
Baking soda - 1/4 tsp
Vanilla essence - 1 tsp
Cardamom Powder - 1/2 tsp

Method:

Preheat oven to 325 degree and grease 9 inch baking tray with oil on sides and bottom and use round wax paper at bottom and grease the wax paper too with oil also.

1.Lightly warm up the milk and dissolve sugar, vanilla, butter and mix oil with it and keep aside. Dont have to heat the milk,warm it enough for sugar to dissolve.
2.Mix all dry ingredients flour, custard powder,baking powder, baking soda,cardamom powder and keep ready
3.Mix wet ingredients to dry ingredients gently , don't over mix ( if you over mix gluten will form and you will end up in bread rather than soft cake) and make it to a smooth batter.Try to use whisk as it will incorporate air without overmixing.As we don't use egg in this cake and custard powder has cornstarch in it you need some air incorporated for a fluffier cake.

4.Pour in tray and put in middle rack and bake for 55 to 60 min until the toothpick inserted comes out clean.(esp check in the middle ).Sometimes the even though the toothpick comes out clean the center may be still raw ,so be sure you keep it in oven for atleast 50 min and if the top is browning cover it with another baking tray or aluminium foil.The crispier crust portion of this cake tastes better so if you like that you can go for it.
5.Let it cool once it's done on a wire rack and after its cool completely cut and serve.