Bloom gelatin sheets in a bowl of ice cold water for 3-5 minutes until gelatin has softened. Remove gelatin from bowl and squeeze out excess moisture. Place gelatin in microwave safe bowl with milk.
Heat milk and gelatin in microwave for 30 second intervals until gelatin has dissolved and milk is warm.
In a large bowl melt together dark chocolate and milk chocolate. Either melt chocolate in the microwave at half power in 30-45 second intervals or over a bain-marie. Once chocolate is smooth and melted, let cool for 5 minutes.
Pour warm gelatin milk mixture into chocolate in three intervals. Fold to combine.
In another bowl, whip heavy cream to soft peaks. Add whipped cream to chocolate mixture in three additions. Fold until combined and there are no white streaks left.
Pour into baked and cooled graham cracker crust. Spread with a mini off set spatula to create an even layer.