1. In a medium saucepan over medium heat, combine the cream, milk, and 1 cup of dulce de leche. Stir until fully blended and the mixture begins to steam, about 4–5 minutes.

2. In a separate large heatproof bowl, whisk together the egg yolks, sugar (if using), vanilla, and salt until smooth.

3. Slowly pour the hot cream mixture into the yolk mixture, whisking constantly to avoid scrambling the eggs.

4. Return the mixture to the saucepan. Stir gently over medium-low heat until thickened into a custard-like consistency (about 6–10 minutes). Do not boil.

5. Strain the mixture through a fine mesh sieve into a clean bowl. Set the bowl into an ice bath to cool, stirring occasionally.

6. Refrigerate the custard for at least 1 hour or until chilled.

7. Pour the chilled custard into an ice cream maker and churn according to the manufacturer’s directions.

8. Once it reaches soft-serve texture, swirl in the remaining ½ cup dulce de leche.

9. Transfer to a freezer-safe container and freeze 3–4 hours until firm.