Goto Edit Html and find the codes below
<title> <data:blog.pageTitle/> </ title><br />
And change with this
<b:if cond='data:blog.pageType == "item"'> <title> <data:blog.pageName/> | <data:blog.title/> </title> <b:else _moz-userdefined=""><title> <data:blog.pageTitle/> </title> </b:else>
oke your save template.