7 steps, about 35 minutes start to finish.
In a medium saucepan, combine the half-and-half and heavy cream. Warm over medium heat until steaming but not boiling.
Meanwhile, whisk the egg yolks and sugar together in a large bowl until pale and slightly thickened, about 2 minutes.
Slowly pour the warm cream mixture into the egg mixture in a thin stream, whisking constantly (this is tempering. It prevents the eggs from scrambling).
Pour the custard back into the saucepan. Cook over medium-low heat, stirring constantly with a wooden spoon, until the custard thickens enough to coat the back of the spoon (about 170–175°F). Do not let it boil.
Remove from heat and stir in the vanilla extract.
Pour through a fine-mesh strainer into a clean bowl. Cover with plastic wrap pressed directly against the surface (to prevent a skin forming) and refrigerate until completely cold, at least 4 hours or overnight.
Churn in your ice cream maker according to manufacturer's instructions. Transfer to a freezer-safe container and freeze for at least 2 hours until firm.
“The base must be completely cold before churning for the best texture. This base is endlessly versatile: add mix-ins, swirls, or flavored extracts before churning.”
