If your egg yolks have been chilling in the refrigerator, remove from the refrigerator and set aside, covered, for 30 minutes to come to room temperature.
Making the Custard
Place egg yolks and caster sugar in a mixing bowl. Whisk together either with a wire whisk or an electric mixer on medium-high speed until light, thick and ribbony.
Place milk, cream and salt in a heavy-bottomed pot. Heat over medium heat, stirring frequently, until the mixture is coming to a boil. Bubbles will start to form around the edges of the pot. Remove the pot from heat.
While whisking the egg-sugar mixture constantly, slowly add in the milk-cream mixture bit by bit followed by a steady stream, until 2/3 of the milk-cream mixture has been added.
Use a silicone spatula and scrape the egg-sugar mixture back into the pot of milk-cream mixture.
Return the pot to low heat and cook, stirring constantly until the mixture thickens, about 5 to 10 minutes. Do not let the mixture come to a boil.
Strain the mixture through a fine sieve and stir in the vanilla paste. Press a clingwrap directly on top of the custard and chill overnight.
Churn the Gelato
Transfer the custard into an ice cream maker and churn according to the manufacturer's instructions.
Serve immediately or transfer the churned gelato into an airtight container and store in the freezer. Let the frozen gelato soften at room temperature for 5 to 10 minutes before serving with chocolate sauce (if using).
NOTES
- Double the quantities used if you want to make 1 quart of ice cream.- Adapted from Italian Food Forever