step1 : Put the butter in saucepan and stir over medium heat until the butter melts.
step2 : Put corn syrup,sugar,brown sugar and condensed milk,stir the mixture to about 20-30 minutes.
step3: Remove from the oven,stir cool slightly,then put the vanilla and stir until to warm enough.
step4: Pour the caramel into a tray was laied with a clear plastic. Wait for until the caramel cool completely.