Place the cream, cocoa powder, and icing sugar into a mixing bowl.
Use an electric mixer and mix at high speed until the cream reaches the consistency you need, soft, medium, or firm peaks (see notes below).
Transfer to a sealed container and store in the fridge until ready to use.
Notes
What are soft and medium peaks?
Soft peak cream forms when the cream has been beaten until it is just starting to hold its shape. The peaks of the cream will droop over when the beaters are lifted. Soft peak cream is used as a topping or garnish.
Medium peak cream forms when the cream has been beaten until it is somewhere in between the soft peak and stiff peak. The peaks of the cream will hold their shape, but they will not be as stiff as stiff peak cream. Medium peak cream can be used as a filling or topping where a little more structure is desired than with soft peak cream, but not as much as with stiff peak cream.
Stiff peak cream forms when the cream has been beaten until it is very stiff and holds its shape well. The peaks of the cream will stand up straight when the beaters are lifted. Stiff peak cream is used as a structural element, such as in piped whipped cream for cakes and other desserts.