Prepare the Fruit: Wash strawberries thoroughly under cool water. Remove the stems and slice into bite-sized pieces. Slice bananas and set aside.
Beat the Cream Cheese: Place softened cream cheese into a large mixing bowl. Using a hand mixer, beat until completely smooth and fluffy. Gradually add powdered sugar and continue beating until silky. Mix in the vanilla extract. The result should resemble a thick cheesecake filling.
Add Sour Cream or Yogurt: Blend in the sour cream (or yogurt) until fully combined. This adds a gentle tang that mimics authentic cheesecake flavor while making the mixture lighter.
Fold in the Whipped Topping: Switch from the mixer to a spatula. Gently fold in the whipped topping using slow, sweeping motions. Avoid stirring aggressively, as this can deflate the airy texture. Your mixture should now look fluffy, smooth, and mousse-like.
Add the Mix-Ins: Carefully fold in the sliced strawberries, bananas, and mini marshmallows. Reserve a few strawberry slices for garnish if desired.
Add Graham Crackers: Stir in most of the crushed graham crackers just before chilling. Save a few tablespoons for sprinkling on top to prevent them from becoming soggy.
Chill the Salad: Cover the bowl and refrigerate for at least 1 hour. Chilling allows the flavors to meld and the texture to thicken beautifully.