Preheat oven to 180°C (356°F) and grease or line a 12 cup muffin pan with cupcake liners. (see note 1).

In a large sized mixing bowl, combine the cocoa powder, salt, flour, and baking powder.

In a separate medium mixing bowl, combine the melted butter (or oil), milk of choice, eggs, and sweetened condensed milk.

Add the wet ingredients to the dry ingredients. Mix until there are no lumps and the mixture is smooth.

Place mixture evenly in prepared muffin pan and bake in preheated oven for about 20 to 25 minutes or until lightly golden brown on top. To check if your cupcakes are cooked, you can carefully stick a wooden skewer or toothpick in the middle of a cupcake. If it comes out clean then the cupcakes are cooked.

Once baked, remove from oven and allow to cool in muffin pan for about 10 minutes before removing them and placing them on a wire cooling rack. Allow to cool completely.

Using an hand mixer or stand mixer, beat the butter on high speed until it becomes pale in color and thick. This should take about 3 to 4 minutes.

Add half of the powdered sugar and cocoa powder. Beat, starting on a lower speed, gradually increasing the speed to high, for about 3 minutes.

Add the remaining icing sugar and cocoa powder. Beat until well combined. This may take about 3 to 4 minutes.

Add the milk and vanilla, beat starting on low speed (so that it doesn’t splash everywhere), gradually increasing the speed to medium/high, for about 1 to 2 minutes.

Place mixture in piping bag and pipe frosting over cooled cupcakes.