Put the butter, brown sugar, cream and salt in a medium saucepan and stir until the butter melts.
Simmer over medium low heat without stirring for three minutes.
Remove from heat and stir in the vanilla extract.
Allow to cool while you make the ice cream base.
To Make the Ice Cream
Warm the butter, brown sugar and half and half over medium until the butter and sugar have melted. Add the sauce and vanilla, still until thoroughly mixed and chill for a minimum of 4 hours; preferably overnight.
Add the heavy cream and process the mixture in an ice cream machine.
Add the toffee bits at the end of processing just to mix them in.
Ripen in a container for a minimum of four hours before serving.
Notes
While this ice cream did freeze, it was never going to get as hard as some I've made but that bit of melting seemed to make it even more accurate...I also remember licking those dribbles that would find their ways down my forearm!