Best Lemon Bars

Serves 4 to 6

  1. Adjust oven rack to middle position and heat oven to 350°F.
  2. Make foil sling for 8-inch square baking pan by folding 2 long sheets of aluminum foil so each is 8 inches wide.
  3. Lay sheets in pan perpendicular to each other, with extra foil hanging over edges of the pan.
  4. Push foil into corners and up sides of the pan, smoothing foil flush to the pan.
  5. Whisk flour, sugar, and salt together in a bowl.
  6. Add melted butter and stir until combined.
  7. Transfer mixture to prepared pan and press into an even layer over the entire bottom of the pan.
  8. Do not wash the bowl.
  9. Bake crust until dark golden brown, 19 to 20 minutes, rotating pan halfway through baking.
  10. While crust bakes, whisk sugar, flour, cream of tartar, and salt together in now-empty bowl.
  11. Whisk in eggs and yolks until no streaks of egg remain.
  12. Whisk in lemon zest and juice.
  13. Transfer mixture into a saucepan and cook over medium-low heat, stirring constantly, until mixture thickens and registers 160 degrees, 5 to 8 minutes.
  14. Off heat, stir in butter.
  15. Strain filling through fine-mesh strainer set over bowl.
  16. Pour the filling over hot crust and tilt pan to spread evenly.
  17. Bake until the filling is set and barely jiggles when the pan is shaken, 8 to 12 minutes.
  18. Let bars cool completely, at least 1 1/2 hours.
  19. Using foil overhang, lift bars out of pan and transfer to a cutting board.
  20. Cut into bars, wiping the knife clean between cuts as necessary.
  21. Before serving, dust bars with confectioners' sugar, if desired.

Lam, Lan. "The Lemoniest Lemon Bars." Cooks Illustrated March & April 2018: 23.