Ingredients

  • For the crust:
  • 8 tablespoons unsalted butter
  • 1/4 cup granulated sugar
  • 3/4 teaspoon vanilla extract
  • 1/4 teaspoon salt
  • 1 cup all-purpose flour
  • For the topping:
  • 1 cup granulated sugar
  • 3 tablespoons all-purpose flour
  • 3 large eggs
  • 2 teaspoons finely grated lemon zest
  • 1/2 cup strained fresh lemon juice
  • Confectioners' sugar, for dusting

Method

  • Preheat oven to 350° F. Line an 8-inch square baking pan with aluminum foil; allow some to hang over the sides of the pan. Lightly grease the foil.
  • To make the crust: Slice the butter into tablespoon-sized pieces. In a light-colored saucepan over medium heat, melt the butter while stirring constantly. The melted butter will foam a bit, then the foam will subside. Keep cooking the butter until the milk solids turn golden brown and the butter has a nutty fragrance, 7 to 10 minutes. Take the butter off the heat and pour it and all the browned bits from the pan into a heat-safe bowl to cool slightly.
  • When the butter has cooled, add the sugar, vanilla, and salt. Add the flour and mix until just incorporated. Press the dough evenly into the bottom of the prepared pan.
  • Bake the crust for 20 to 25 minutes, until it is golden brown.
  • Meanwhile, make the topping: Stir the sugar and flour together. Whisk in the eggs, followed by the lemon zest and juice.
  • When the crust is done, turn the oven down to 300° F. Slide the oven rack with the pan on it out of the oven and pour the filling into the hot crust. Slide the rack back into the oven and bake until the topping is set and does not jiggle in the center when the pan is tapped, 20 to 25 minutes. Set the pan on a rack and let the bars cool completely in the pan.
  • Lift the cooled bars out of the pan, using the foil as handles. Slice the bars into 16 or 25 squares and dust with confectioners' sugar just before serving. Store leftover bars in the fridge for up to a week. The crust will soften over time.