1. Cut kernels from ears of corn; set cobs aside. Combine kernels and 1 cup milk in a blender; process until smooth. Combine corn mixture, remaining 2 cups milk, sugar, and salt in a medium, heavy saucepan. Cut cobs into thirds; add cobs to pan. Heat corn mixture over medium heat to 180° or until tiny bubbles form around edge (do not boil). Remove from heat; let stand 1 hour. Discard cobs.
2. Return pan to medium heat; heat to 180°. Combine half-and-half and egg yolks in a medium bowl, stirring with a whisk. Gradually add half of hot milk mixture to egg mixture, stirring constantly with a whisk. Pour egg yolk mixture into pan with remaining milk mixture; cook over medium heat 2 minutes or until a thermometer registers 160°, stirring constantly. Pour mixture through a fine sieve over a bowl, pressing lightly with a wooden spoon; discard solids. Place bowl in a large ice-filled bowl. Cool completely, stirring occasionally. Pour mixture into the freezer can of an ice-cream freezer; freeze according to manufacturer's instructions. Spoon ice cream into a freezer-safe container. Freeze 1 hour or until firm.