Step 1

In a large bowl, whisk together the egg yolks and the sugar aggressively until the mixture is thick and pale yellow in color. It should fall from the whisk in thick ribbons.

Step 2

Combine the milk, cream, and vanilla in a large saucepan and bring to a boil. Remove from the heat immediately, and temper it slowly into the egg mixture, whisking with your other hand.

Step 3

Return mixture to the saucepan and cook slowly over low heat until custard base thickens slightly, and coats the back of a wooden spoon. Remove from heat and place over an ice bath. Continue to stir every few minutes until the mixture is cold.

Step 4

Meanwhile, bring a large pot of salted water to a boil (the salt will keep the basil leaves very green). Blanch the basil leaves, drain in a fine-meshed sieve over an ice bath, and squeeze out any excess moisture. Puree the basil leaves in a small food processor, and stir into the cooled ice cream base. Allow the mixture to infuse for several hours or overnight.

Step 5

Strain the ice cream base through a fine-meshed sieve to remove any larger pieces of basil leaves. Freeze the ice cream according to your ice cream maker’s manufacturer’s directions. Place the ice cream in an airtight container and cover the surface with plastic wrap. Freeze for 4 to 6 hours or until firm. Allow ice cream to soften just slightly before serving.