In a medium saucepan over medium heat, add granulated sugar and let it melt without stirring, swirling occasionally. Cook until it turns a golden amber color, about 8–10 minutes.

Stir in unsalted butter until fully melted and smooth. Gradually whisk in heavy cream, allowing the mixture to bubble for a minute, then stir in sea salt.

Remove from heat and set aside to cool completely.

In a mixing bowl, whisk together egg yolks and sugar until thickened and pale, about 2–3 minutes.

In a separate saucepan, heat milk and remaining heavy cream over medium heat until just simmering. Gradually pour the hot mixture into the egg yolks, whisking constantly.

Transfer everything back to the saucepan and return to medium-low heat.

Cook the custard, stirring frequently, until it thickens enough to coat the back of a spoon, around 10–12 minutes.

Remove from heat and strain the mixture through a fine mesh sieve. Chill the custard base in the fridge for at least 1 hour.

Once chilled, pour the custard base into your ice cream maker and churn according to the manufacturer's instructions, about 20–25 minutes.

Gradually drizzle in the cooled caramel sauce to create beautiful ribbons of flavor.

Transfer the ice cream to an airtight container, pressing cling film against the surface. Freeze for at least 4 hours or until solid.

Store in the freezer for up to two weeks.