Yes, ASP.NET 4.5 is supported by Parallels Plesk Panel (PP) 11.

Below are the lists of ASP.NET versions supported by PP versions:

 

PP 9.5:

 

PP 10.4:

• ASP.NET 1.1 - 4.5

Note #1: as .NET 4.5 Framework is iterative update to .NET 4.0, Parallels Plesk Panel and IIS will continue displaying available version of ASP.NET as 4.0.

Note #2: See KB article #115727 for instructions on how to set up .NET 1.1 Framework on Windows 2008 with IIS7.

This information was taken from the applicable release notes:

 

PP 9.5 Release Notes

PP 10.4 Release Notes

PP 11.0 Release Notes