Melt half the chocolate chips and spread them in a 9x13 lightly greased cake pan.
Break up shortbread cookies into big pieces and layer on top of the chocolate.
Toast Coconut (if needed) set aside.
In 2-quart saucepan over medium-low heat, combine butter, sugar and corn syrup.
Heat to a full boil, stirring constantly with a wooden spoon.
Boil 3 minutes, stirring constantly.
Slowly pour in sweetened condensed milk, stirring constantly.
Continue cooking over low heat until candy thermometer reaches 220-228 degrees.
Remove from heat.
Stir in vanilla.
Beat until creamy.
Immediately stir in toasted coconut and mix well.
Spoon mixture over shortbread cookies and spread.
Melt remaining chocolate chips and drizzle thinly over cookies and let chocolate harden at room temperature.
Cut into squares.
Store in airtight container.