How do I retrieve AppSettings from the assembly config file?

I would like to retrieve the AppSetting key from the assembly config file called: MyAssembly.dll.config. Here's a sample of the config file:

<configuration>
    <appSettings>
        <add key="MyKey" value="MyVal"/>
    </appSettings>
</configuration>

Here's the code to retrieve it:

var myKey = ConfigurationManager.AppSettings["MyKey"];