2Tbsp powdered sugar, plus more for dusting, see Recipe Notes
¼tsp kosher salt
⅓cuplemon juice, freshly squeezed, from 2 lemons
2Tbsplime juice, freshly squeezed, from 1 lime
1Tbsppeppermint, fresh, finely chopped
¼cup all-purpose flour
Preheat oven to to 325°F. Lightly coat a 9- x 9-inch baking pan with baking spray or butter. Line the dish with a parchment paper sling, leaving an overhang of about 2 inches on two opposite sides; set aside.
Make the crust: Place the flour, granulated sugar, powdered sugar, and salt in the bowl of a food processor fitted with the blade attachment. Pulse 5 times to combine. Sprinkle with the butter cubes and pulse until the mixture looks like coarse crumbs.
Pour the crust mixture into the prepared baking dish. Using a pastry dough tart tamper or your fingers, press the crumbs into an even, tight layer. Refrigerate for 15 minutes.
Bake the crust until light golden-brown, 25 to 30 minutes.
Make the filling: While the crust is baking, place the whole eggs, egg yolk, granulated sugar, powdered sugar, and salt in a large bowl and whisk to combine. Whisk in the lemon juice, lime juice, mint, and flour until just combined (try not to overmix).
Remove the parbaked crust from the oven. Pour the filling onto the warm crust. Make sure to tap out any air bubbles on the counter before baking.
Return the pan to the oven and bake until light brown around the edges, set in the middle, and the top appears relatively dry, 15 to 20 minutes. Cool completely on a wire rack, at least 1 hour, before removing from pan.
Using a fine-mesh strainer, generously dust the bars with powdered sugar (see Recipe Notes).
Move the bars to a cutting board by grasping the parchment sling and lifting the slab out of the pan. Cut into 12 or 16 bars. Dust with more powdered sugar, if desired, before serving.
These bars are best eaten within 24 hours, but may be covered and refrigerated for up to 3 days.
I forgot to tap out the air bubbles in the filling, so they just baked into the finished product. I made a note in the recipe to remind you and me.The finished bars sucked up the powdered sugar, even though I kept adding more and more. Just sprinkle on some when you’re just about to serve them. Or better yet, get some non-melting Topping Sugar from King Arthur Flour...it works really well! (I'm not sponsored by King Arthur Flour, I just like their products).