Lemon-Ginger Cake with Pistachios

Whisk eggs and yolks in large bowl. Combine lemon juice, butter, and sugar in medium metal bowl. Set over saucepan of simmering water; stir until sugar dissolves. Gradually whisk hot lemon mixture into egg mixture. Return mixture to bowl set over water; whisk constantly until mixture thickens and instant-read thermometer registers 180 °F, about 5 minutes. Pour curd through fine strainer set over bowl; stir in lemon peel. Place plastic wrap directly on surface of curd. Refrigerate until cold, at least 8 hours or overnight. (Can be made 2 days ahead. Keep refrigerated.)