For the berry syrup:
Combine the blackberries, lemon juice, and sugar in a medium-sized saucepan.
Bring the mixture to a boil over medium heat. Reduce to a steady simmer and cook for 8-10 minutes until it begins to get syrupy and berries start to lose their shape. Set aside to cool completely.
For the cream layer:
Combine the gelatin and water in a small microwave-safe bowl and stir well. Microwave for 15 seconds, stir, and set aside to cool slightly.
In a medium-sized clean bowl, whisk the cream for 1-2 minutes until it starts to thicken a bit. Add the gelatin mixture, powdered sugar, and vanilla and continue whisking till soft peaks form, about 2-3 minutes more.
Place yogurt in a medium-sized bowl and fold in the whipped cream until combined.
To finish:
Layer the blackberry syrup and the cream mixture in 6 clear glass bowls, jars, or glasses (¾-1 cup each). Garnish with fresh berries and mint leaves.