Prepare the Cranberry Layer by rinsing fresh cranberries under cold water; combine cranberries with water and sugar in a saucepan, cooking until cranberries burst.

Make the Shortbread Crust by preheating oven to 350°F. Combine melted butter, sugar, vanilla, and salt in a bowl; stir in flour to form a dough and press it into a baking dish.

Assemble the Layers by pouring cooled cranberry mixture over crust, spreading evenly, and refrigerating for about 45 minutes.

Create the Lemon Layer by whisking together eggs, granulated sugar, flour, and lemon juice; pour over cranberry layer.

Bake in preheated oven at 350°F for 20-25 minutes until lemon layer is set. Cool completely and then refrigerate for at least 1-2 hours.

Serve chilled, dusted with powdered sugar, cut into squares, and enjoy at room temperature.