- With the rack in the middle position, preheat the oven to 350°F (180°C). Line the bottom of an 8-inch (20 cm) springform pan with parchment paper.
- In a food processor, finely grind the cookies to the texture of bread crumbs. Transfer to a bowl, add the butter and combine. Lightly press onto the bottom and halfway up the sides of the prepared pan. Bake for 10 minutes or until lightly browned. Let cool.
- Meanwhile, in a small bowl, sprinkle the gelatin over the water. Let bloom for 5 minutes.
- In a small saucepan over medium heat, heat the mango purée. Stir in the gelatin until it has dissolved. Set aside in a large bowl and let cool to room temperature, about 15 minutes.
- In another bowl, whip the cream and sugar using an electric mixer until firm peaks form. Set aside the whipped cream in the refrigerator.
- Using a spatula, stir the yogurt into the mango purée. Gently fold in the whipped cream and spoon onto the crust in an even layer. Refrigerate for 4 hours until the mousse has set, or freeze, if desired.
- Twist the mango slices into spirals and place on the cake. Run the blade of a knife between the cake and the pan. Unmould and serve.
For 1 cup (250 ml) of mango purée, process 2 cups (340 g) of cubed mango in a blender until smooth, then strain.