Preheat the oven to 350°F (175°C). In a mixing bowl, combine the flour, shredded coconut, and powdered sugar. Add the softened butter and mix until crumbly.

Stir in the egg yolk and cold water until the dough comes together. If the dough is too dry, add a little more water, one teaspoon at a time.

Press the dough into a 9-inch tart pan evenly across the bottom and up the sides. Prick the bottom with a fork to prevent bubbling.

Bake the crust for 15-20 minutes or until lightly golden. Remove from the oven and let it cool completely.

In a saucepan over medium heat, combine the coconut milk, granulated sugar, cornstarch, vanilla extract, and salt. Whisk until smooth and cook until the mixture thickens, about 5-7 minutes.

Remove the saucepan from heat and fold in the diced mangoes. Pour the filling into the cooled tart crust and spread evenly.

Refrigerate the tart for at least 2 hours to set.

Before serving, top with whipped cream and garnish with fresh mint leaves if desired.