In a large mixing bowl, whisk together the vanilla pudding mix, milk, and vanilla extract until smooth. Refrigerate for about 10 minutes to thicken.
In a trifle dish or large glass bowl, layer half of the ladyfinger cookies at the bottom.
Spoon half of the vanilla pudding mixture over the ladyfingers, spreading it evenly.
Add a layer of half of the sliced strawberries, blueberries, and raspberries on top of the pudding.
Repeat the layers with the remaining ladyfingers, pudding, and mixed berries.
Top the final layer with whipped cream, spreading it evenly.
Garnish with fresh mint leaves if desired. Chill in the refrigerator for at least 1 hour before serving.