Chill the mixing bowl and whisk attachment in the freezer for about 10 minutes.
Pour the heavy cream into the chilled bowl and beat with an electric mixer on medium-high speed until soft peaks form.
Gradually add the confectioners' sugar, cocoa powder, and vanilla extract. Start beating on low speed to incorporate the ingredients, then increase to high speed and continue beating until stiff peaks form.
Use the chocolate whipped cream immediately as a topping for desserts or beverages.