This was such a fun project, and so easy! We cultured the cream with plain yogurt for a little over 24 hours. Then we used the food processor to turn it to butter. I was surprised at how quickly it changed (5 minutes or less). Since we were trying cultured butter, we decided to only add salt. We wanted the pure flavor to come through. It's not a strong flavor, so I wouldn't want to hide it with herbs. I wonder if culturing it for a longer time would enhance it. Either way, it was delicious. For the mold, we used soap molds that we already had. You can probably see the mold didn't come out perfectly clean, but it's still rather pretty, don't you think?