Key limes are one of those citrus fruits that are only sold in grocery stores during certain months. This is because they have thinner skin and don’t keep as long as other varieties. But, they also have a more intense flavor than Persian limes- the latter being the variety that’s available year-round in the supermarket. You can make this recipe with either variety and both will yield that slightly floral, tart flavor that limes are loved for. But, if you can find key limes then use those for a more intense flavor.
These little limes get their name from Florida keys, but originally they were known as Mexican limes. After a particularly harsh winter in 1894-95, they were planted to replace the damaged lemon trees. In the 1920s they were largely replaced by the hardier Persian limes and today key limes are quite the treat.
FOR THE SHORTBREAD:
1 1/2 sticks salted butter room temperature
1 1/2 cups all-purpose flour
1/3 cup powdered sugar
FOR THE TOPPING:
2 eggs, room temperature
juice of 3-4 key limes or regular limes (about 1/4 cup), strained
1 1/4 cups granulated sugar
1/4 cup all-purpose flour
2 teaspoons cornstarch
1 teaspoon vanilla extract
1/4 teaspoon baking powder
1/8 teaspoon salt
1 teaspoon key lime zest
powdered sugar and/or extra lime zest for garnish
PREPARATION
Preheat oven to 350˚F. Mix dough ingredients until crumbly dough forms. Press this into an 8”x8” baking dish lined with parchment paper, taking it 1/2” up the sides as well. Bake for 15-20 minutes.
Beat eggs until foamy then add lime juice, granulated sugar, flour, cornstarch, vanilla, baking powder, and salt. Mix until no lumps remain, then stir in lime zest. Pour filling into crust while it’s still warm. Return to oven and bake for 25-28 minutes or until center is no longer jiggly.
Allow to set in the refrigerator for at least 1 hour before adding a dusting of powdered sugar and some extra lime zest on the top. Then cut into 16-25 squares to serve.
