Preheat oven to 350 degrees Fahrenheit and grease an 8 to 9" tart pan.
Combine all crust ingredients in the bowl of a stand mixer fitted with the paddle attachment.
Beat on medium-high speed until the ingredients come together to form a ball of dough.
Evenly press the tart crust dough into the greased tart pan and up the sides.
Use a fork to prick the crust in several places.
Bake until golden brown -- about 15 minutes.
Remove from the oven and cool completely before filling with cranberry curd.
In a small saucepan, bring the cranberries and water to a boil.
Reduce heat and simmer 5 minutes, using the back of a wooden spoon to smash the cranberries into mush as they cook.
Pour the mashed cranberries into a fine mesh sieve over a bowl and use the back of a wooden spoon to press the puree through the sieve. You should have 1 cup of cranberry puree when finished.
Add the cranberry puree back to the saucepan over medium heat.
Add the butter (or palm shortening), sweetener, and salt.
Whisk over medium heat until totally smooth.
Remove from the heat and whisk in egg yolks and vanilla until smooth.
Pour into the baked and cooled tart crust.
Let set in the refrigerator at least 30 minutes or until ready to serve.
Best served within 2 days. Keep leftovers covered and refrigerated.