I finally planted an herb garden this year and want to make and freeze some various herb butters to preserve the flavors. I was planning to mix up various kinds and freeze in ice cube trays, then in plastic bags. We happen to have quite a bit of butter in the freezer now, but perhaps it's not a good idea to thaw it, make herb butter and re-freeze? Does anyone have any advice on this? Has supermarket butter been frozen before?

Favorite recipes welcome!