Preheat the oven to 350 degrees F or 180 degrees C for at least 10 minutes.

Melt the butter in a microwave or on the stovetop. Do not let it boil. heat the butter till it is just melted. Let it cool down to room temperature.

Now prepare the 9 inch round cake pan. Brush the bottom and sides of the pan using melted butter and keep it aside.

Take dry ingredients (all purpose flour, cocoa powder, baking powder, and baking sodin a bowl. Mix well using a wire whisk. Keep it aside.

Add water, condensed milk and vanilla extract to the melted, cooled butter. Whisk well till everything is incorporated well.

Now sift the half of the flour mixture into the wet mixture. Whisk it till incorporated.

Now sift the remaining flour mixture. Again mix it. Halfway through switch to the spatula. And stir till it is just combined, do not overmix.

Pour the batter into the prepared cake pan. Lightly tap it on the countertop. So batter will spread out evenly and if there are any air bubbles, it will also get removed.

Bake into the preheated oven for 30 minutes.

Check the cake by inserting a toothpick in the center of the cake. If it comes out clean that means cake it ready.

Remove it from the oven and put on the wire rack. Let it cool down for 10 minutes in the pan itself.

Then Invert the cake upside down to the cooling rack.

Let the cake cool down completely on wire rack. It will take about 1 to 1 ½ hours depending on the weather.

Roughly chop the chocolate into small pieces and take into a bowl. Keep it aside.

Take heavy cream and butter in a pan. Turn the heat on medium.

Bring the mixture just to a boil. As soon as it comes to a boil, turn off the stove.

Pour the hot cream mixture into the chocolate bowl.

Let it stand without disturbing for 2 minutes. By this time chocolate will get melted.

Then start whisking the mixture.

Keep whisking till it geta shiny, smooth and everything is incorporated well.

Now put the cake with a rack on the baking tray. So you will not have messy countertop and tray will catch the excess drip.

Pour the ganache on the cake.

Using a butter knife, spread it evenly and let it cover the sides as well.

Let the ganache frosting set for 1-2 hours.

Then slice the cake.