Set a sieve over a mixing bowl; set aside.
Combine yolks and sugar in a medium bowl and whisk for 2 minutes, or until thick; set aside.
In a medium saucepan, combine milk and cream and set over medium heat; cook until mixture begins to bubble on the sides; remove from burner.
Slowly whisk the milk mixture into the egg yolks mixture; continue to whisk until combined.
Pour the entire mixture back into the saucepan and cook over medium heat, stirring constantly, until mixture leaves a coating on the back of a spoon, about 5 to 7 minutes, or reaches a temperature of 170-degrees fahrenheit. (I almost always use a thermometer when making gelato).
Remove from heat and pour the mixture through the previously prepared sieve.
Stir in the vanilla.
Cover the bowl with plastic wrap and refrigerate for 4 hours.
In the meantime, prepare the caramel sauce.
Combine caramels, butter and sweetened condensed milk into a saucepan.
Cook over medium-low heat until melted, stirring constantly; about 5 minutes.
Remove from heat; set aside and let cool completely.
Remove custard from fridge and pour the mixture into your ice cream maker.
Freeze the mixture in your ice cream maker according to the manufacturer’s instructions.
In the last 3 minutes of freezing, and while the ice cream is churning, pour about 2-ounces of the caramel sauce into the ice cream machine. You can use less or more caramel sauce - that is up to you.
When finished churning, transfer the gelato to an airtight container.
Freeze for 5 hours, or until firm.