Gluten-Free Lemon Bars
MAKES 10-12 BARS
1 1/3 cups all-purpose gluten-free flour, divided (I use Better Batter)
1/2 teaspoon xanthan gum (omit if using Better Batter)
1/2 cup confectioners sugar, plus more for dusting
1/2 teaspoon kosher salt
9 tablespoons (1/2 cup + 1 tablespoon) unsalted butter, melted and cooled
2 extra-large eggs
1 cup granulated sugar
1/2 teaspoon baking powder
1/3 cup fresh squeezed lemon juice (2 to 3 lemons)
1 1/2 teaspoons corn starch
1. Preheat your oven to 350 degrees Fahrenheit. Grease an 8- or 9-inch baking pan with butter or shortening, line with criss-crossed pieces of parchment paper that overhang the sides, and grease the parchment paper. Set the pan aside.
2. In a medium-sized bowl, combine the flour and xanthan gum. Measure out 1/3 cup of the mixture and set it aside in a small bowl. To the remaining 1 cup flour, add the confectioners sugar and salt, and whisk to combine. Add the butter and mix with a fork until crumbly but moist. It should stick together when squeezed. If it seems a bit too dry (and this will depend upon the environment in your kitchen), drizzle in a tablespoon of milk until it is moist enough to hold together when you squeeze it with your hands. Press the mixture into the bottom of the prepared baking dish, and about halfway up the sides of the dish.
3. Place the baking dish in the center of the preheated oven and bake for 15 to 20 minutes, or until uniformly pale golden. If you have already baked it for 20 minutes, but it is still not uniformly golden, turn down the temperature to 325 degrees and continue to bake until it reaches the desired color.
4. While the crust is in the oven, make the custard. In a medium-sized bowl, whisk together the eggs, granulated sugar, baking powder, lemon juice, remaining 1/3 cup flour, and corn starch. Whisk until the mixture thickens a bit.
5. Allow the crust to cool for a few minutes after baking. Then, pour the custard into the baked crust, and return to the center of the oven and bake at 350 degrees for about 30 minutes, or until set (it is set when the center doesn’t jiggle when you shake the pan).
6. Cool in the pan for about 20 minutes, dust with powdered sugar, and then cool in the refrigerator until firm, about 2 hours and up to overnight.
7. Run a butter knife or thin spatula around the perimeter of the baking dish, and then lift the bars out of the pan by the overhung pieces of parchment paper. With a large serrated knife, cut into 9 or 12 squares.
8. Serve chilled.