Beat the eggs until fluffy for about 2 minutes.
Add the sugar and vanilla and carry on whisking for a further 3 minutes or so until the sugar is incorporated and the colour is pale.
Add the cream and whisk until it thickens - about 3 minutes.
Add the milk and mix to combine
Run the mix through an ice cream maker until ready according to the manufacturer’s instructions. The KitchenAid ice cream bowl works quickly and takes about 15 minutes.
Chop up the millionaire shortbread into smallish chunks. It doesn't matter if the shortbread, caramel and chocolate separate and fill 2 cups.
Once the ice cream has reached its set point in the machine, add the pieces and churn very briefly and only until it has been combined.
Decant into a freezer-proof container, sprinkle over a few more bits of chopped-up millionaire shortbread (optional) and freeze until ready to serve. It will also firm up a bit more.