Creating a Berry Trifle is simple when following these steps:

1. Prepare the Berries: Rinse the mixed berries under cold water and pat them dry. Slice the strawberries if using.

2. Whip the Cream: In a large bowl, combine the heavy whipping cream, powdered sugar, and vanilla extract. Whip until soft peaks form.

3. Layer Ingredients: Select a large glass bowl or individual serving cups for layering. Begin with a layer of sponge cake cubes at the bottom.

4. Add Pudding Layer: Spoon a layer of vanilla pudding over the cake cubes, making sure to cover them evenly.

5. Include Berry Layer: Add a layer of mixed berries on top of the pudding, spreading them out evenly.

6. Repeat the Layers: Continue layering the cake, pudding, and berries until you reach the top, finishing with a layer of whipped cream.

7. Chill: Cover with plastic wrap and refrigerate for at least 2 hours, allowing the flavors to meld.

8. Garnish: Just before serving, add a dollop of whipped cream on top and garnish with fresh mint leaves if desired.

These straightforward steps will guide you to create a beautiful and delicious Berry Trifle that will leave everyone asking for seconds!