A friend had a bottle of Bailey's Salted Caramel Cream over Christmas. It seems to have been a limited edition and she asked if I could try to recreate it. I haven't entirely succeeded in that but some of my experiments have been a hit with the taste testers. (There is no shortage of volunteers who are willing to try my concoctions!)
Essentially I used milkshake syrup/ice cream topping, "neutral" and long life cream. So one bottle of Hershey's caramel syrup ( about 600ml) mixed with 500ml neutral (40%) and 400 ml ( 2 cartons) of long life cream. A similar version with Hershey's Chocolate Topping was also popular. Best made a few days before you want to drink it. Quantities can be altered to suit personal preferences and whatever syrup or topping or cream you happen to have. I cannot comment on how long it might keep as it all disappeared very quickly.