In a large mixing bowl, combine the heavy whipping cream, powdered sugar, and vanilla extract. Use an electric mixer to whip the mixture until it forms stiff peaks. Set aside.
Rinse the mixed berries gently under cold water. Pat them dry with a paper towel, and if using strawberries, remove the stems and slice them in half.
In a trifle bowl or a large glass dish, start by adding a layer of vanilla sponge cake cubes at the bottom.
Spoon a layer of vanilla yogurt over the sponge cake, spreading it evenly.
Add a layer of mixed berries over the yogurt, distributing them evenly.
Dollop half of the whipped cream mixture over the berries, smoothing it out with a spatula.
Repeat the layering process with another layer of sponge cake, yogurt, berries, and finish with the remaining whipped cream on top.
Cover the trifle with plastic wrap and place it in the refrigerator for at least 2 hours to allow the flavors to meld and the cake to soak up some moisture.
Once chilled, remove the trifle from the fridge. Garnish the top with fresh mint leaves and a few extra berries for a pop of color.