In a medium bowl, whisk together the pudding mix and cold milk until smooth and slightly thickened. Let it rest for 5 minutes to firm up.
Create a base layer of vanilla wafers or graham crackers in a glass dish or individual cups.
Slice bananas and layer them on top of the cookies. Spoon a generous amount of pudding over the fruit, spreading it evenly.
Layer sliced strawberries over the pudding, then spread a fluffy layer of whipped topping.
Repeat the layers until your dish is full, ending with whipped topping and optional extra fruit or crushed cookies on top.
Refrigerate for at least 1 hour before serving. Best served chilled.