Is it really you?

What you're looking for is a combination of Master Pages and web user controls. Master Pages to control the overall layout of the page, and a user control which can sit in any page which accepts values (public properties) which in turn are used to populate the various asp:literal and asp:label controls in the web user control.

You have to keep in mind that the way templates worked in PHP (string replacement) is due to the fact that PHP was script-based rather than object oriented, and so the way things are done in ASP.NET are different. Which means that the same feature is implemented differently when you're doing it in ASP.NET.

Another option, for example, would be to have as you said an XSLT file which you can then .Transform() and get a rendered output.