Preheat oven to 350°F/177°C. Line a 9x13-inch baking pan with parchment paper.
In a mixing bowl, whisk together the gluten-free flour blend, xanthan gum (if using), powdered sugar, and kosher salt. Stir in the melted butter.
Add the dough into the prepared baking pan, breaking it into pieces. Then press the dough into the bottom of the pan until it is an even thickness.
Bake at 350°F/177°C for 24-27 minutes, until the crust is golden brown. Let cool while preparing the fillings.
To make the cranberry filling, place the fresh cranberries, granulated sugar, water and lemon zest in a medium saucepan.
Bring to a boil over medium heat, stirring occasionally, until the berries burst and turn into a jammy consistency, about 7-8 minutes. Set aside.
To make the lemon filling, whisk together the granulated sugar, gluten-free flour blend, lemon zest, eggs and lemon juice until smooth and no clumps of flour remain.
Spread the cranberry filling over the baked crust and spread until it’s an even layer.
Pour the lemon filling over the cranberry layer.
Bake at 350°F/177°C for 25-30 minutes, or until the lemon layer is mostly set but jiggles slightly when you shake the pan.
Let cool to room temperature and then refrigerate for at least 3 hours before slicing. Dust with powdered sugar before serving if desired.
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Notes
The nutrition values here are based on cutting these cranberry lemon squares into 12 pieces. You can cut them smaller if you like.
I used Bob’s Red Mill 1-to-1 Gluten-Free Baking Flour for this recipe, which already contains xanthan gum. You do not need to add xanthan gum if your flour blend already contains it.
You’ll need approximately 4 medium/large lemons for this recipe. You’ll use both the zest and the juice of the lemons for various parts of the recipe.
You can use fresh or frozen cranberries in this recipe. No need to let frozen cranberries thaw before placing in the saucepan.
Gently pour the lemon filling over the cranberry jam to try not to disturb it so that you get two distinct layers. Don’t fret too much over the cranberries popping up over the lemon layer though a bit. You’ll still have two separate layers.
You don’t necessarily need the parchment paper to line the pan. You can instead grease your pan with butter or cooking spray. I prefer the parchment paper because it makes it easy to remove them from the pan and place onto a cutting board to slice the bars when ready.