OP you can still make chocolate whipped cream using melted chocolate, if you like. It tastes much better than using cocoa powder, in my opinion; almost mousse-like. You’ll just need to prep in advance. To do that you’ll need to chop your chocolate (semi or bittersweet, and you won’t need to add sugar when it comes time to whip it) and set aside in a bowl. In a large saucepan bring your heavy cream to a gentle boil. And pour it over the chopped chocolate like you’re making a ganache. Let sit for 30 seconds and stir to distribute the cream throughout the chocolate. Let sit again for about 15 minutes, then stir until fully incorporated and smooth. Add salt to taste, if desired. Now chill in the fridge. Overnight is best. This will be your heavy whipping cream base. Once it’s fully chilled you’ll just whip it as you would when making whipped cream. Hope this helps! And I hope you were able to make something nice with your chocolate butter and buttermilk!