Step 1

Prepare an ice-water bath. Combine milk, cream, 1/2 cup sugar, the espresso, and vanilla in a saucepan. Bring to a simmer over medium heat.

Step 2

Meanwhile, whisk together egg yolks and remaining 1/2 cup sugar in a bowl.

Step 3

Gradually whisk half the hot milk mixture into the egg-yolk mixture. Pour egg-yolk mixture into saucepan, and whisk. Cook over medium heat, whisking constantly, until thick enough to coat the back of a spoon.

Step 4

Strain through a fine sieve into a heatproof bowl set in ice-water bath. Let cool, stirring occasionally. Press plastic wrap on surface of custard to prevent a skin from forming, and refrigerate 2 hours.

Step 5

Freeze in an ice cream maker according to manufacturer's instructions. Transfer to an airtight container, and freeze for at least 1 hour before serving.