I love making these. They're called French Butter Bells, French Butter Crocks, French Butter Dishes. Call them what you will, but know this - they work! These decorative two-part dishes help keep softened butter from spoiling without the need for refrigeration. C'est vrai!
Basically you soften a stick of butter. Smoosh the butter into the cup that hangs upside down ffrom the lid. (Unfortunately you can't see that in the picture.) Put a little water (1/2" or so) in the cup you can see so that when the lid is put back on, the cup underneath makes contact with the surface of the water, forming a seal that keeps any bad stuff from getting in your butter and making it yucky! Quelle science!!
For me, it's a 3-fer. I get to throw two pieces to make one butter bell. And then I can carve, as you see here on the lid in the photo. Magnifique!
They make great gifts and look gorgeous on the counter or table. French Butter Bells! Who knew?!