An air cooled turbine airfoil such as a stator vane in which the airfoil is hollowed out and an insert is secured within the hollowed out section that produces sequential impingement cooling of the airfoil. The insert is formed from a plurality of plates bonded together outside of or inside of the airfoil to form a single piece insert with the cooling circuit. The plates are bonded together using TLP bonding process with sheets of boron placed between adjacent plates so that no excess material seeps out and into the cooling features formed with the plates. The cooling features of the plates are formed by photo-etching.