Globally keyed cache fragments across all controllers

In the documentation for fragment caching (Caching with Rails: An Overview — Ruby on Rails Guides), this is stated:

  If you don’t want the cache block to bind to the action that called it, You can also use globally keyed fragments by calling the cache method with a key, like so:

  <% cache('all_available_products') do %>     All available products:   <% end %>

  This fragment is then available to all actions in the ProductsController [...]

Is it possible to add a globally keyed cache fragment that is available in _all_ controllers, not just ProductsController as in the example above? I plan on having a list of the top 10 items of one of my models, in my layout, so it'd be ideal to have that cached globally.