Mix, but don't whip all ingredients (except snails). Heat mixture in a large skillet. Add snails and simmer for 10 to 15 minutes, allowing liquid to cook into snails. Preheat oven to 350 degrees. Put small amount of butter mixture into bottom of each shell, insert by using a fork, continue until all shells are filled. Place in shallow baking dish. Pour remaining mixture over snails and bake until bubbling (about 10 minutes).