In a mixing bowl, combine crushed chocolate sandwich cookies with melted unsalted butter. Stir until the mixture resembles wet sand, then press it firmly into silicone or ring molds, creating an even layer. Place the molds in the freezer for about 15 minutes.

In a saucepan, combine fresh or frozen blackberries with sugar and water over medium heat. Stir occasionally until the blackberries break down, approximately 5-7 minutes. Blend the mixture until smooth and strain through a fine mesh sieve.

In a small bowl, bloom the gelatin by sprinkling it over lemon juice. Gently warm until dissolved, then mix into the warm blackberry purée. Allow this to cool to room temperature.

In a separate bowl, whip the heavy cream until soft peaks form, then gently fold in the vanilla extract and the cooled blackberry-gelatin mixture.

After the crusts have set, pour the blackberry mousse over the chilled cookie bases in the molds. Smooth the tops evenly and refrigerate for at least 4 hours.

To create the glaze, heat heavy cream, pour it over white chocolate chips, and let sit before stirring until smooth. Allow to cool slightly.

Remove the cakes from molds, drizzle the glaze over each cake, and garnish with fresh blackberries and edible flowers just before serving.