How to use a french butter dish (aka “butter bell” 

This video shows how to use a French butter dish.
I make them myself, and you can find them on my Etsy page when I have them in stock.
Essentially, you pack the butter into the lid, fill the bottom about halfway with water, and place the lid filled with butter into the base, making sure the lid submerges down into the water.
This creates a vacuum seal which prevents the butter from going rancid at room temperature. Then, you can have soft spreadable butter whenever you like!
It also has the added bonus of protecting your butter from cats and other critters.
Change the water once or twice a week, as needed.
*If you use unsalted butter, put some salt into the water.