Combine whole milk and heavy cream.
Separately combine egg yolks and cornstarch.
Cook brown sugar and water in a heavy bottomed pan. Slowly add the milk mixture to the pot, bringing to a boil.
Add the egg yolk mixture to the pan, tempering it first by adding some of the boiling pudding to the egg yolk mixture. Then pour it all back into the pudding.
Remove from heat and whisk in the remaining ingredients. Place into serving glasses and cool.
Once pudding is cooled, top with whipped cream and crushed toffee bar.