Use this recipe when making the Cinnamon-Mocha Ice Cream Cake with Chocolate Crunchies.
Prepare an ice-water bath.
Combine milk, 1/2 cup sugar, espresso, salt, and vanilla in a saucepan. Bring to a simmer over medium heat.
Meanwhile, whisk together egg yolks and remaining 1/2 cup sugar in a medium heatproof bowl.
Gradually whisk half the hot milk mixture into the egg-yolk mixture. Pour egg-yolk mixture into saucepan, and whisk. Cook over medium heat, stirring constantly, until thick enough to coat the back of a spoon -- about 4 minutes. Add heavy cream.
Pour through a fine sieve into a heatproof bowl set in ice bath. Let cool, stirring occasionally.
Place plastic wrap on surface of custard to prevent a skin from forming, and refrigerate 2 hours or overnight.
Freeze in an ice cream maker according to manufacturer's instructions.