Expanding Archives adds a new widget that shows your archive of posts in an expandable, collapsible menu. Posts are sorted and grouped into their years and months of publication.
The plugin comes with minimal styling so it’s very easy to customize and tweak to match your design.
You can find the plugin available for free in the WordPress.org repository. Inside your admin panel, go to Plugins » Add New and search for Expanding Archives. Or, click the button below to download it:
Screenshots
The widget on the Nose Graze blog.
Expanding Archives widget on the Twenty Fifteen theme.
The widget settings (there are none!).