Steamed moist chocolate cake

Name: Steamed moist chocolate cake
Prep time: 10 min
Cook time: 45 min
Total time: 55 min
Yield: 4
Cuisine: En
Ingredients: 150g unsalted butter; 170g fine sugar; 200ml evaporated milk; 2 eggs, lightly beaten; 125g plain flour; 70g cocoa powder (I used Valrhona Brand); 1-/2 tsp baking powder; 1/2 tsp baking soda; 1/2 tsp vanilla essence; 35g cocoa powder, sifted; 50gm corn flour, sifted; 1 cup evaporated milk; 2 egg yolks; 175ml water; 120g sugar; 1 tsp vanilla extract; 50g unsalted butter