In a medium sized saucepan, simmer and smash the raspberries and sugar for 10 minutes, or until the raspberries become soft
Remove from the heat and stir in the tapioca flour slurry. Stir until thickened.
Strain the raspberry sauce through a strainer, into a bowl, to remove the seeds. Set aside until the bars are baked.
Preheat the oven to 350℉.
In a food processor, pulse to combine flour, cornstarch, sea salt, and butter.
Grease the 13x9 glass baking dish.
Pour the ingredients from the food processor into the baking dish and evenly spread over the bottom of the dish, pressing down to form a crust.
Bake the shortbread for 18 minutes.
While the shortbread is baking, mix together the lemon filling ingredients.
In a mixing bowl, combine the eggs, sugar, flour, lemon zest, lemon juice, and heavy cream.
Once the shortbread is finished baking, remove the baking dish from the oven.
Pour the lemon filling on top of the shortbread and return the dish to the oven.
Bake again for 20 minutes.
Remove the baking dish from the oven and allow the bars to cool for 30 minutes before adding. the raspberry topping.
Once the bars are slightly cooled, pour the raspberry topping over the entire bars.
Cover and refrigerate for 30 minutes before slicing.