Create a blank page in your project and have it inherit from your base class. Then create your own Visual Studio template from that page which you can then use to create new pages going forward in your project.
Here are a couple of articles which walk you through how to do this: http://msdn.microsoft.com/en-us/library/vstudio/tsyyf0yh.aspx and http://msdn.microsoft.com/en-us/library/vstudio/ms185311.aspx