using sql server 2005

I have a stored procedure with a temp table where I am trying to insert values as shown below but when I do so I am getting an error, it seems that my single quotes are off, does anyone know the correct syntax that I need to do?

the error:

<ERROR>

Msg 105, Level 15, State 1, Line 1
Unclosed quotation mark after the character string ',TestC)'.
Msg 102, Level 15, State 1, Line 1
Incorrect syntax near ',TestC)'.

</ERROR>

and the code that is causing the error:

DECLARE @DynamicINSERTSQL nvarchar(300)
DECLARE @VarA nvarchar(50)
DECLARE @VarB NVARCHAR(2)
DECLARE @VarC nvarchar(50)

--I am setting the variable values after I declare them
SET @VarA = 'Test A'
SET @VarB = 'Test B'
SET @VarC = 'Test C'

 --this is the line below that errors out
SET @DynamicINSERTSQL = 'INSERT INTO #MyTempTable(ColumnA, ColumnB, ColumnC) VALUES (''' + @VarA + ''',' + @VarB + ''',' + @VarC + ')'
EXEC(@DynamicINSERTSQL)