Place the softened butter in a bowl and beat until it becomes light and fluffy. This can be done in a stand mixer or with a hand mixer in a large bowl.
Turn the mixer down to low speed and gently add the icing sugar and then the cocoa powder and mix until fully incorporated.
Add the vanilla extract and mix through.
Gently mix through 2 tablespoons of milk.
When incorporated, turn the speed up on the mixer and whip until light and fluffy.
If the icing seems too thick, add a little of the extra milk until you get a spreadable consistency.
Nutritional information is an estimate and provided as a courtesy. The values may vary according to the ingredients and tools that are used. Please use your preferred nutritional calculator for more detailed information.