In a large bowl add the heavy cream. Begin whipping on high with a stand mixer or hand mixer.
Once the cream has roughly doubled in size and soft peaks begin to form, add in the ¼ oz gelatin packet and 6 Tbsp powdered sugar. Continue to beat until stiff peaks form.
If making chocolate whipped cream add 1 Tbsp cocoa powder and whip until evenly incorporated. For a richer cocoa color and flavor add more cocoa powder (up to 1 Tbsp more). The cocoa powder will add a bit of bitterness, so taste and add more sugar as needed, up to 12 Tbsp.
Transfer to a piping bag with desired tip, and pipe as needed. Keep refrigerated. In the piping bag can last up to 5 days in the fridge (though it may begin to get a little grainy). Can keep on a cake, in the refrigerator anywhere from 1-3 days, depending on moisture content of your cake and fridge.