Homemade butter, including flavored butter.
Basically, just pour the cream in a jar with a tight lid and enough room to get a nice agitation going. Keep shaking until butter forms. Pour out buttermilk. You might want to either let it sit for a minute or so in a tight mesh strainer to get the rest of the milk out or use butter paddles or a mould. Recruit your kids (if you have any) for the shaking part.
You can add herbs or honey to flavor. I've done honey butter. I add the honey at the start so it goes all through the butter. Haven't tried it with salt, though, so I'm not sure how much is enough to preserve without overpowering the flavor of the butter.