01 - Place softened cream cheese in a large mixing bowl and beat until completely smooth and creamy, approximately 2 minutes.
02 - Incorporate powdered sugar and vanilla extract into the cream cheese, continuing to beat until the mixture becomes fluffy and fully combined.
03 - In a separate chilled bowl, whip cold heavy cream using electric beaters until stiff peaks form, being careful not to overbeat.
04 - Gently fold the whipped cream into the cream cheese mixture using a rubber spatula, incorporating until smooth and uniform in texture.
05 - Add quartered strawberries, blueberries, and mini marshmallows to the creamy base. Gently fold together until all ingredients are evenly coated.
06 - Transfer the mixture to a serving bowl and refrigerate for at least 1 hour to allow flavors to meld and texture to set.
07 - Serve chilled and garnish with additional fresh berries if desired. For best quality, enjoy within 24 hours of preparation.