Lemon Custard

Directions

1. 1
   In a medium bowl, whisk together the whole egg, egg yolk, lemon juice, and 1/4 cup sugar.
2. 2
   In a medium saucepan, combine the lemon zest, milk, remaining 2 tablespoons sugar, cornstarch, and salt.
3. 3
   Bring to a boil over medium-high heat, whisking constantly.
4. 4
   Remove from heat; slowly pour about a third of the hot milk mixture into the egg mixture, whisking constantly until combined.
5. 5
   Pour mixture back into remaining milk, whisking constantly.
6. 6
   Return saucepan to medium-high heat.
7. 7
   Whisking constantly, cook until mixture is bubbling in the center and thick enough to hold a deep trail when stirred with a wooden spoon, about 2 minutes.
8. 8
   Strain mixture through a fine sieve into a medium bowl; whisk in butter.
9. 9
   Press a sheet of plastic wrap directly on the surface of the custard to prevent a skin from forming.
10. 10
    Let cool completely.
11. 11
    Cover and refrigerate until ready to use, up to 1 day.