Yes, there is a way to achieve a shutdown with one click.  Here is what you do:

First, get to the main desktop screen.   Next, right click on the desktop and select New –> Shortcut.  When the menu appears, click ‘Create new Shortcut.’ When Windows 8 asks you what item you’d like to create a shortcut for, enter the following command: ‘shutdown /s /t 0’. (By the way, that’s a zero. Also, make sure not to include a period or the quotations.) Then click ‘Next.’

Enter a name for the new shortcut (‘Shutdown’ is a good choice) and click ‘Finish.’

Next, right click on your brand new shortcut and then left click on ‘Properties.’ A new dialog box will appear.   Click ‘Change Icon.’ When Windows 8 tells you that ‘The file C:\Windows\System32\shutdown.exe contains no icons, click ‘OK.’

You’ll now be asked to select an icon from a list of images. Pick the one that suits you best.

Once you’ve done that, right click the shortcut again. Select ‘Pin to Start.’ Now your brand new, customized shutdown icon will appear continuously on the operating system’s Start screen.

You can repeat all of these steps to create a new Restart shortcut, as well. The only difference: after selecting ‘Create new Shortcut’ you’ll have to enter the command ‘shutdown /r /t 0’ (zero again). The “r” is for “Restart.”