In a small bowl, whisk together egg yolks and sugar until thick and pale. Add a few tablespoons of warm milk mixture to egg mixture, whisking vigorously. Once combined, add egg mixture back into milk mixture, whisking continuously.
Return to saucepan; cook over medium-low heat, stirring constantly with a large heat-proof rubber spatula until custard thickens enough to coat the back of a spoon (a mark should remain when you run your finger down spoon). Alternatively, cook until an instant thermometer reads 175° to 180°. Do not allow mixture to boil.
Strain custard through a fine mesh sieve into a glass bowl; discard solids. Cover and refrigerate at least 1 hour, or up to 1 day. (To quicken chilling time, place glass bowl in a larger bowl filled with ice water until custard thickens slightly and is completely cool to touch.)
Freeze custard according to ice cream maker instructions. Transfer to airtight container and freeze up to 2 days, removing ice cream from freezer about 10 minutes before serving to soften. Or serve immediately after making.