In a small heavy saucepan, heat milk to 175°; stir in sugar until dissolved. Whisk a small amount of hot mixture into egg yolks. Return all to the pan, whisking constantly. Add lemon peel. Cook over low heat until mixture is just thick enough to coat a metal spoon and a thermometer reads at least 160°, stirring constantly. Do not allow to boil.
Remove immediately from heat; stir in lemon juice and cream. Place in a bowl. Press plastic wrap onto surface of custard; refrigerate several hours or overnight. Stain mixture in to the frozen ice cream cylinder, about two-thirds full; freeze according to the manufacturer’s directions.
Recipe by The Glitzy Pear at https://theglitzypear.com/2017/08/how-to-make-homemade-lemon-gelato-in-your-own-kitchen/