Make the Blackcurrant (Cassis) Puree:

• Rinse and remove stems from fresh blackcurrants, or slightly thaw frozen berries.
• Place blackcurrants and water in a saucepan over medium-low heat.
• Cook gently, stirring occasionally, until berries soften (5-7 minutes).
• Blend the cooked berries until smooth using a blender or immersion blender.
• Strain through a fine mesh sieve to remove seeds for a smoother puree (optional).
• Cool the puree completely before use.

Make the Crust:

• Combine graham cracker crumbs, melted butter, and sugar in a bowl until the mixture resembles wet sand.
• Press the mixture evenly into the bottom and up the sides of an 8-inch springform pan.
• Refrigerate the crust for at least 30 minutes to set.

Make the Mousse:

• Place 2 tablespoons of water in a small microwave-safe bowl and sprinkle gelatin evenly over it. Set aside for 5 minutes to bloom.
• In a separate bowl, beat cream cheese until smooth, then add sugar and beat until fluffy.
• Gently fold in whipped cream until completely incorporated.
• Microwave gelatin for about 10 seconds until liquid. Quickly whisk gelatin into the cream cheese mixture until smooth.
• Divide mousse equally into three bowls. Keep one plain. Add 50 grams of cassis puree to one bowl and 100 grams to the third bowl (or 40 and 80 grams for a less tart flavor).
• Layer mousse in the crust: first plain mousse, then lighter cassis mousse, swirling gently for an ombré effect. Finish with the darker mousse, smoothing the top evenly.
• Refrigerate overnight.

Decorate the Cake:

• Sprinkle 3 grams gelatin powder over 1 tablespoon water; let sit 3 minutes.
• In a saucepan, boil remaining 3 tablespoons water with sugar until dissolved. Add gelatin mixture, stirring until completely dissolved.
• Cool glaze slightly, then carefully arrange edible flowers atop the mousse.
• Spoon glaze gently over flowers and mousse.
• Chill cake for at least 2 hours before serving.