The original piece that was used to make this icon was made by ~TheUkelele as seen here -
To make the icon, the box was removed from the cake on original piece and then put onto a transparent background. This PLZ account, was made by someone else; just a fan of cute pixels. Especially pixels that are fun to be used for PLZ decorations.
To use, merely copy-paste the bold code where you want this to show.
Thank you theukelele for creating such a beautiful pixel cake and at a great size too! n.n