Add the 20 ounces of chopped chocolate to a medium bowl, heat 1/2 cup of heavy whipping cream until hot and pour over the chocolate. Let it stand for 1 minute, stir to combine. If needed microwave for 30 seconds and stir until the chocolate is fully melted. The mixture should be smooth and shiny. Set aside to cool.
In a large bowl, using an electric hand mixer or stand mixer, beat cream cheese, add sugar on medium-low speed until combined. Stop a few times to scrape the sides and bottom of the bowl.
Add cocoa powder and mix until combined.
In a chilled mixing bowl, add the remaining 2 cups of cold heavy whipping cream. Whip on high speed until stiff peaks form.
Manually, using a spatula, fold the whipped cream into the cream cheese mixture. Make sure it's all combined, beat on low speed for 1-2 minutes.
Add in the vanilla extract and gelatin mixture to the bowl, mix on low-medium speed to combine.
Add the melted chocolate to the batter, mix on low-medium speed to combine. Using a spatula scrape the sides and bottom of the bowl.
Spread the cheesecake filling onto the prepared pan. Level the top with a spatula.
Set the cheesecake in the refrigerator to chill and firm, 6-8 hours or better, overnight.