01 - Place softened cream cheese in a large mixing bowl. Beat with electric mixer until completely smooth and creamy, scraping down sides as needed.
02 - Add powdered sugar and vanilla extract to the cream cheese. Beat on medium-high speed until fully incorporated and mixture becomes fluffy, about 2 minutes.
03 - In a separate chilled bowl, whip cold heavy cream using electric mixer or stand mixer until stiff peaks form. Be careful not to overwhip.
04 - Gently fold whipped cream into cream cheese mixture using rubber spatula. Fold until smooth and uniform, maintaining as much air as possible.
05 - Add quartered strawberries, blueberries, and mini marshmallows to the cheesecake mixture. Gently fold to combine until all ingredients are evenly coated.
06 - Cover bowl with plastic wrap and refrigerate for at least 1 hour before serving. This allows flavors to meld and mixture to achieve proper texture.
07 - Serve chilled in individual bowls or glasses. Optionally garnish with additional fresh berries just before serving.