For the crust :

In a laarge bowl, combine all the ingredients for the crust, until the texture resembles wet sand.

Press mixture into bottom of 6-inch springform pan, pressing down with back of mug or spoon.

For the mousse :

With the gelatin leaves:

Soak them in colld water until softened, about 5 minutes. Then remove the excess water and stir in hot milk until the gelatin dissolves.

With gelatin powder:

Sprinkle the powder over hot milk. Cook the milk-gelatin mixture in a double boiler until dissolved.

Then pour the hot milk-gelatin mixture over the mascarpone cheese.

Stir in the sugar, then stir in the whipped cream.

Using a blender, grind the frozen blueberries to form a powder.

Stir in the water tto make a thick paste.

Divide the mousse mixture between 4 bowls. Stir the blueberry paste into 3 of the bowls, making 3 different shades of purple.

Pour the white foam in the center of the mold. Continue with each shade of purple mousse, going from lightest to darkest. (Optional: draw patterns in the cake using a wooden skewer.)

Refrigerate for at least 4 hours before serving.