- beat 1 stick butter + 60 g powdered sugar
- add 128 g all-purpose flour, 72 g almond flour, and pinch salt
- bake for 20 minutes at 350°F
- 4 large egg yolks (74 grams)
- 150 g sugar
- 94 g lemon juice (about 2 1/2 large lemons)
- 4 tablespoons unsalted butter (softened) (2 ounces = 57 grams)
- Pinch of salt
- 2 teaspoons lemon zest (finely grated) (4 grams)
- 2 tablespoons powdered sugar for dusting (0.5 oz = 14 grams)
- In a heavy noncorrodible saucepan, beat the egg yolks and sugar with a wooden spoon until well blended. Stir in the lemon juice, butter, and salt.
- Cook over medium-low heat, stirring constantly, for about 6 minutes, until thickened and resembling hollandaise sauce, which thickly coats a wooden spoon but is still liquid enough to pour. (A candy thermometer will read 196°F.)
- The mixture will change from translucent to opaque and begin to take on a yellow color on the back of a wooden spoon. It must not be allowed to boil or it will curdle. (It will steam above 140°F. Whenever steaming occurs, remove the pan briefly from the heat, stirring constantly to prevent boiling.)
- When the curd has thickened, pour it at once into the strainer. Press it with the back of a spoon until only the coarse residue remains. Discard the residue. Stir in the lemon zest.
- When the shortbread is baked, remove it from the oven, lower the temperature to 300°F., pour the lemon curd on top of the shortbread, and return it to the oven for 10 minutes.
Adapted from Rose Levy Beranbaum and someone else