In a large mixing bowl, combine the all-purpose flour and powdered sugar until evenly mixed. Add the chilled, cubed butter to the bowl. Using your fingers or a pastry cutter, mix until the mixture resembles coarse crumbs.
Stir in the egg yolk and cold water. Mix gently until the dough starts to come together. If needed, add an extra teaspoon of cold water to achieve the right consistency.
Press the dough into a tart pan with a removable bottom, ensuring an even layer across the base and up the sides. Use a fork to prick the bottom gently for even baking. Chill the tart shell in the refrigerator for about 30 minutes to firm up.
Preheat your oven to 375°F (190°C). Once preheated, bake the tart shell for 15 minutes, or until it's lightly golden on the edges. Remove from the oven and set aside to cool.
In a clean mixing bowl, use an electric mixer to beat the softened cream cheese and granulated sugar together until the mixture is smooth and creamy, with no lumps remaining.
Add the orange zest, freshly squeezed orange juice, cornstarch, vanilla extract, and eggs into the cream cheese mixture. Mix on low speed until everything is well combined and smooth.
Carefully pour the orange filling into the cooled tart shell. Use a spatula to spread the filling evenly across the surface.
Place the filled tart back into the preheated oven. Bake for 25–30 minutes, or until the filling sets but is still slightly jiggly in the center. Keep an eye on it to prevent overbaking.
Allow the tart to cool completely at room temperature. Once cooled, refrigerate the tart for at least 2 hours before serving to enhance the flavors and set the filling.
Notes
Before serving, dust the top of the tart with powdered sugar and garnish with orange slices and mint leaves.