Pour the heavy cream into a heavy saucepan. Add sugar and stir to combine. Bring the mixture to a simmer over low heat, stirring occasionally.

In a separate bowl, scramble the egg yolks and milk until mixed. Temper the egg yolks by slowly drizzling in about half of the hot cream mixture while whisking quickly. Pour the tempered egg yolk mixture back into the saucepan, whisking gently as you add it. Simmer over low heat until it gets very thick, 5 to 7 more minutes.

Pour the mixture through a fine mesh strainer into a medium bowl, pressing with a spoon or spatula to gently force it through. Stir in vanilla. Cover and refrigerate this mixture 8 hours (or overnight) until it's cold.

Churn the mixture in an ice cream maker according to its directions. After the cycle is completed, stir in any fruit or other add-ins and immediately transfer to a freezer container and place in the freezer. A couple of hours later, open the container and stir again to make sure it's distributed.

Freeze for another 24 hours or until frozen hard and solid.