01 - 
                In a small saucepan, combine blackberries, granulated sugar, and lemon juice. Cook over medium heat for 5-7 minutes, stirring occasionally, until the blackberries are soft and release their juices. Strain the mixture through a fine-mesh strainer, pressing with a spoon to extract as much juice as possible. Discard the seeds and let the puree cool to room temperature.
              
              
              
                02 - 
                In a large mixing bowl, whip the cold heavy cream with powdered sugar and vanilla extract until stiff peaks form.
              
              
              
                03 - 
                Gently fold the cooled blackberry puree into the whipped cream until fully combined, creating a light, fluffy mousse.
              
              
              
                04 - 
                Spoon or pipe the blackberry mousse into dessert cups or bowls. Smooth the tops.
              
              
              
                05 - 
                Refrigerate for at least 2 hours to allow the mousse to set. Garnish with fresh blackberries, a dollop of whipped cream, and mint leaves if desired.