 Yes, a whisk attachment works the best for this. And if everything is at room temperature, it really works great. So you'll start up by kind of whipping that butter until it's really creamy and white. Then you add your sugar. And at that point, it almost looks like an American buttercream. It's really creamy and it kind of looks spreadable, but it's really too sweet. So then you drizzle in an entire cup of heavy cream and it's actually going to curdle. And you'll think it's wrong, but if you keep beating for about 10 minutes, you're going to get this really luscious buttercream.