Learn the best gluten-free baking tips for making homemade lemon squares with a tender, flaky crust. This no-fail gluten-free lemon bars recipe uses a simple technique for a perfectly-set lemon custard on a crisp, buttery base, all baked to perfection. The ideal sweet and tangy citrus topping sits on a classic shortbread crust, which can be quickly blended together in a food processor or mixer.
Preheat the oven to 350ºF. Line an 8X8" pan with a large piece of foil, pressed firmly to the bottom and the sides with enough overhang to lift the bars out after baking. Set aside.
For the crust, use a food processor or stand mixer fitted with paddle attachment. On low speed combine the flour, sugar, and salt.
1 ⅓ cup gluten free all purpose flour, ⅓ cup granulated sugar, ¼ teaspoon salt
Add the softened butter to the dry ingredients, one tablespoon at a time, blending completely between each addition. The dough should pull away from the sides of the bowl and come together without any dry crumbs.
8 tablespoons unsalted butter,
Pour in the prepared baking pan, pressing firmly into an even layer. Bake for 20-25 minutes, rotating halfway through, until lightly golden brown. Remove from oven, leaving oven on, while the filling is prepared.
For the filling, use a medium saucepan to whisk together the sugar, flour, cream of tartar, and salt. Add the eggs, egg yolks, lemon zest, and lemon juice. Whisk to combine.
1 cup granulated sugar, 2 tablespoons gluten free all purpose flour, 2 teaspoons cream of tartar, ¼ teaspoon salt, 3 large eggs + 3 egg yolks, 2 teaspoons grated lemon zest, ⅔ cup fresh lemon juice
Cook over medium-low heat, stirring constantly, until the mixture until the mixture thickens and reaches a temperature of 160ºF, about 5-7 minutes. (I use my favorite instant read thermometer to check quickly.)
Remove from the heat and stir in the butter. Pour the hot filling over the baked crust.
4 tablespoons unsalted butter
Return to the oven for 10-12 minutes, or until the edges are raised and the filling barely jiggles when the pan is gently shook. Cool the bars to room temperature, then chill for 2 hours in the pan. Lift the bars out of the pan by the foil handles and cut into bars. Dust the tops with powdered sugar and serve. Refrigerate leftovers in an airtight container.
Notes
How to tell when lemon bars are done baking
The bars should have a raised edges and the middle should be set. It will still jiggle a little when the pan is shook, but shouldn't slosh around.
For best results, cool the bars completely on a wire rack and then at least 2 hours before cutting and serving.
Storing
Store cut lemon bars in the refrigerator in an airtight container. Upon sitting, the powdered sugar will seep into the filling, so you may want to dust them again upon serving.Crust recipe adapted from The How Can it Be Gluten Free Cookbook and filling adapted from Cook's Illustrated