Format Date Column in dynamic Pivot query in SQL Server

I write the following query. and the datatype for ExamDate is varchar(50)

            DECLARE @cols AS NVARCHAR(MAX),
            @query  AS NVARCHAR(MAX)
            select @cols = STUFF((SELECT ',' + QUOTENAME(ExamDate) from tblDateSheet 
            group by ExamDate order by ExamDate FOR XML PATH(''), TYPE ).value('.', 'NVARCHAR(MAX)') 
                    ,1,1,'')
            set @query = 'SELECT ExamType,ClassName,SectionName,STime,' + @cols + ' from 
                         (
                            select ExamType,ClassName,SectionName,SubjectName,STime,ExamDate
                            from tblDateSheet as dts inner join tblDefClass as dc on dts.ClassID= dc.ClassID inner join tblDefSection as ds on dts.SectionID=ds.SectionID
							inner join tblAssignSubjects as si on dts.SubjectID=si.ASID inner join tblDefSubject as dsb on si.SubjectID=dsb.SubjectID
							inner join tblSetExam as se on dts.SetExamID= se.SetExamID ) x
                        pivot 
                        (
                            max(SubjectName)
                            for ExamDate in (' + @cols + ')
                        ) p '
            execute(@query);

it is showing output like this

but i want output like this