Add the coffee to the milk in a jug, still well and cover
Leave in the fridge overnight to cold brew, at least 12 and up to 18 hours.
To strain the coffee line a strainer with a place a piece of cheese cloth or other suitable clean material. Place the strainer over a bowl and strain the coffee milk mix. pressing the coffee and then squeezing the cloth to get out as much coffee milk as possible
You should have about ½ of very strong cold brew coffee milk.
Add cream and condensed milk to a bowl. Beat with electric hand beaters until soft peaks start to form.
Slowly add coffee milk mix, about a third of it at a time, beating well in between additions
Try to ovoid the last few sips in the bottom which will be full of sediment.
If using, add the alcohol and beat in well until soft peaks start to form again.
Tip into a container and freezer until set or overnight.
Remove from freezer, scoop and enjoy!