Also known as a butter bell or crock, the French butter keeper originated in France, in an area known for its pottery. It is an elegant solution for always having spreadable butter on hand, while also keeping it fresh at room temperature for weeks. The keeper consists of a lid resembling a bell which holds the butter, and a base into which the lid fits. You fill the base with about a half-inch of water, which creates an airtight seal for the lid when placed into the base. Then you pack cold butter tightly into the lid and place in the water-filled base, making sure the water rises over the mouth of the bell when submerged. This way, no oxygen interacts with the butter and thus helps preserve it, eliminating the need for refrigeration. Enjoy spreadable butter on a warm, crusty baguette!
Use real butter; the finer the better.
Pack the butter in the lid when it is still fresh out of the refrigerator; it is easier to mold at a cooler temp.
Keep the house cool. As long as your home stays below 80°F, the butter can last up to a month.
Change the water weekly (or more frequently for longer-lasting results).
Salted butter lasts longer than unsalted butter, but if using unsalted, add a pinch of salt to the water in the base and that will prevent mold.
Remove any food crumbs from the butter leftover from your spreading knife before replacing into the base.
If your butter slides out of the bell, not to worry. Completely dry off the butter ball with a paper towel, and dry off the inside of the bell as well. Re-pack your butter ball into the bell, eliminating any air holes.