Make the Tart Crust

1. Prepare the Dough: In a mixing bowl, combine flour, powdered sugar, and salt. Add the cold cubed butter and mix until the mixture resembles coarse crumbs.
2. Add Egg Yolk: Stir in the egg yolk and enough ice water to form a dough. Wrap in plastic wrap and refrigerate for 30 minutes.
3. Roll Out Dough: Preheat the oven to 350°F (175°C). On a lightly floured surface, roll out the dough to fit a 9-inch tart pan. Press the dough into the pan and trim any excess.
4. Blind Bake: Prick the bottom of the crust with a fork. Place parchment paper over the crust and fill with pie weights or dried beans. Bake for 15 minutes, then remove the weights and bake for an additional 10 minutes or until golden. Let it cool.

Prepare the White Chocolate Filling

1. Melt Chocolate: In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer. Remove from heat and add the chopped white chocolate. Stir until melted and smooth.
2. Combine Eggs and Vanilla: In a mixing bowl, whisk together the eggs and vanilla extract. Gradually add the melted chocolate mixture to the eggs, whisking continuously to prevent curdling.
3. Fill Tart Crust: Pour the filling into the cooled tart crust. Bake at 350°F (175°C) for 20-25 minutes or until the filling is set but slightly jiggles in the center. Let it cool.

Prepare the Cranberry Topping

1. Make Cranberry Sauce: In a saucepan, combine cranberries, sugar, water, lemon juice, and cinnamon (if using). Cook over medium heat until the cranberries burst and the mixture thickens, about 10 minutes. Remove from heat and let cool.
2. Top the Tart: Once the tart is cooled, spread the cranberry sauce evenly over the white chocolate filling.

Chill and Serve

1. Chill Tart: Refrigerate the tart for at least 1 hour before serving to allow the flavors to meld.
2. Serve: Slice the tart and serve chilled. Enjoy your delightful Cranberry White Chocolate Tart!