How to get Menu Item Teaser Image in Page Template layout

{% GetFileUrlByGUID(CurrentDocument.GetValue("MenuItemTeaserImage", string.Empty), "File Name") |(identity)GlobalAdministrator%}

That is a macro that will pull the image. If you want to use it in a transformation, you should be able to use <%# GetFileUrl(Eval("MenuItemTeaserImage")) %>

Then you should be able to put the answer of those into a src tag of an image.

You can also use the <%# GetImage("NewsTeaser") %> transformation method helper.

Click here for transformation helper methods.

Is that what you're looking for?

Using code blocks <%...%> in ASCX layout can cause issues. It is not supported. I would recommend using HTML layout and macros like suggested by Alex. Or, use SCRIPT tags and inside them use standard C# and API on the page load event to get the teaser image. Or, create a custom web part which will do the job.