Step 1

Place the sugar in a medium skillet and place over moderate heat. Heat, stirring constantly with a fork, until the sugar begins to melt and turn a deep caramel color. Be careful, once the sugar turns to liquid form, this will happen quickly.

Step 2

Immediately remove the caramel from heat and very slowly pour the milk into the caramel, be careful it may sputter. The caramel will immediately seize and harden - do not worry. Return the mixture to low-medium heat, stirring frequently until all the caramel has dissolved.

Step 3

In a separate bowl, whisk together the egg yolks and cornstarch. Temper the egg yolk mixture with the hot caramel milk, pouring slowly, while whisking constantly with your other hand. Transfer the mixture to a medium saucepan and cook over medum heat, stirring constantly with a wooden spoon. Allow the mixture to come to a low boil, stirring constantly, for 2 minutes. As the cornstarch is brought to heat, the mixture will begin to thicken until it is the texture of pudding. Remove from the heat.

Step 4

Strain the mixture through a fine-meshed sieve into a large heat-proof bowl. Set the bowl in an ice bath, stirring every 10 minutes or so, until the base has cooled. Place ice cream base in an airtight container and set in the refrigerator until it has completely chilled. Once the mixture has cooled, cover surface with plastic wrap and place in fridge for at least one hour or overnight.

Step 5

Once cooled, whisk in the cold cream and vanilla extract. Churn the ice cream in an ice cream maker according to the manufacturer’s instructions. In the last five minutes of churning, add the finely chopped chocolate. Transfer the ice cream to an airtight container, cover the surface of the ice cream lightly with parchment paper or plastic wrap. Freeze for an additional 4 to 6 hours before serving.