Adjust oven rack to upper-middle position and heat oven to 375 degrees. Place tart pan with shell on cookie sheet.

In medium non-reactive bowl, whisk together yolks and whole eggs until combined, about 5 seconds. Add sugar and whisk until just combined, about 5 seconds. Add lemon juice, zest, and salt; whisk until combined, about 5 seconds. Transfer mixture to medium non-reactive saucepan, add butter pieces, and cook over medium-low heat, stirring constantly with wooden spoon, until curd thickens to thin saucelike consistency and registers 170 degrees on an instant-read thermometer, about 5 minutes. Immediately pour curd through single-mesh stainless steel strainer set over clean non-reactive bowl. Stir in heavy cream; pour curd into warm tart shell immediately.