Place water, cranberries, and 6 tablespoons of sugar in a medium saucepan, bring to a boil over medium-high heat. Reduce heat to low, simmering, stirring occasionally, until cranberries start to burst. About 15 minutes.
Continue to simmer, stirring and breaking up any whole cranberries - a wooden spoon works great for this. Cook until cranberries are completely broken down, with no whole pieces remaining, about another 10 minutes. Remove from heat, cooling for 30 minutes.
Prepare Lemon Shortbread Crust
Meanwhile, preheat the oven to 350 degrees F and line a 9 inch square baking pan with parchment paper. Lightly coat pan and parchment with cooking spray.
In a medium-large mixing bowl, stir together 1 ⅓ cups flour, ¼ teaspoon salt, powdered sugar, ½ cup granulated sugar, and lemon zest until combined. Mix in butter cubes, using a pastry cutter or your fingers (you may also do this step in a food processor). Once the mixture looks like sandy crumbs that stick together when pinched, press into the bottom of the prepared pan. Bake for 20-30 minutes until golden brown, remove and allow to cool slightly, about 20-30 minutes.
Once cooled, spread the cooled cranberry mixture over the crust, chill for 30 minutes, meanwhile make the lemon layer.
In a medium-large mixing bowl, whisk together the lemon juice, 1 ¼ cups granulated sugar, ⅓ cup flour and ¼ teaspoon salt. Add lightly beaten eggs to the mixture, whisking until combined, frothy and lighter in color. Set aside until ready to use.
Once the cranberry layer has chilled on the crust, remove from the fridge and give the lemon layer once last good stir, pour evenly over the top of the cranberry mixture. Bake in a 350 degree oven 40-45 minutes until the center is set, it may jiggle slightly. Remove from oven, allowing to cool completely on a wire rack.
For best results, once cooled, chill in fridge for 12 hours before slicing, this will allow time for the layers to settle and firm up.
Using the parchment paper to lift the bars from the pan, place on a cutting board and cut into 9, 12 or 16 squares. Sprinkle if desired with powdered sugar before serving. These are also beautiful served with a few sugared cranberries.
StorageStore these cranberry lemon bars in an airtight container in a single layer, or lay a piece of parchment between layers. They will keep well for up to 7 days.
TO FREEZE: Make sure they are cooled completely first, place on parchment paper and then on pan and flash freeze for one hour until firm. Then wrap well in plastic wrap and again in foil or place in an airtight baggie. Freeze up to 3 months, thaw in fridge overnight.
Doubling the recipe | Double ingredients and bake in 9x13 inch pan, baking 5-10 minutes longer covering with foil if browning too much.
*If using all-natural cane sugar in lemon layer, be sure to whisk until sugar is completely dissolved, so you don't end up with a gritty lemon layer.May be doubled, bake 5-10 minutes longer if needed, covering with foil to prevent over browning. **Leftover cranberry sauce may be used for cranberry layer, you will need about a cup. Or canned whole cranberry sauce may be used as well -- be sure to stir it well first to break up a bit. Gluten-Free Cranberry Lemon BarsUse 1 cup almond flour and ⅓ cup coconut flour as a substitute. The curd-like topping can be thickened with tapioca starch or coconut flour. You may also use a good gluten-free all purpose flour; but in shortbread I have found that I like almond flour better!