Peel the mangoes and dice into 1/2-inch cubes, discarding the mango pit. In a large bowl, combine the diced mango, sugar, crystallized ginger, mint, lime zest and juice and a pinch of salt. Gently stir the fruit until it is well coated. Cover and refrigerate for at least an hour.
In a large mixing bowl of a stand mixer, combine the whipping cream with the confectioners' sugar, vanilla and a pinch of salt. Whip the cream to medium peaks. Fold in the creme fraiche by hand with a rubber spatula, being careful not to over work the cream.
To serve, layer the Shortcake Biscuits in a wide-mouth tall glass (like a rocks glass), top with fruit and then whipped cream. Repeat with a second layer. Garnish with fresh mint and serve immediately.
Preheat the oven to 375 degrees F. Line a baking sheet with parchment paper.
In a large mixing bowl, whisk together the flour, granulated sugar, baking powder and salt until well mixed. Using two knives or a pastry cutter, blend in the cold butter cubes until the mixture resembles a coarse crumb. (You may also do this in a food processor, using the pulse button.)
Form a well in the flour mixture. Beat the egg and cream together and pour into the well. Mix with a fork until the mixture just comes together. Turn the dough out onto a lightly floured work surface. Form the dough into a ball and gently knead with four to five turns until the dough is formed and smooth. Do not over work the dough or the shortcake will be tough.
Gently roll the dough out to 1/2-inch thickness. Using a small 1 to 2-inch cookie cutter (I like a star shaped one), cut out the shortcake and place on the prepared baking sheet spaced at least 1-inch apart. (Or you may use a knife and cut the shortcake into 1-inch squares.) Brush the shortcake lightly with cream and sprinkle with the sanding or demerara sugar. Bake until the shortcakes are golden brown and cooked through, 12 to 15 minutes. Transfer to a wire rack to cool. Store in a dry, air-tight container for up to 2 days. Toast the shortcakes lightly in the oven to bring back to life.