1. Prepare the sponge cake:
If you're using store-bought sponge cake, cut it into cubes (about 1-inch). If you’re using ladyfingers, break them into pieces that will fit into your trifle dish.

2. Layer the trifle:
In a large trifle dish or individual glasses, start by layering the cubed sponge cake at the bottom. You can lightly drizzle the cake with some fruit juice or a little bit of berry syrup for added flavor if desired.

3. Add the custard layer:
Spoon a generous layer of the cooled vanilla custard over the sponge cake.

4. Add the whipped cream:
Whip the whipping cream with the powdered sugar and vanilla extract until soft peaks form. Spread a thick layer of whipped cream over the custard.

5. Add the berries:
Evenly distribute the strawberries, blueberries, and raspberries on top of the whipped cream.

6. Repeat the layers:
Continue layering the cake, custard, whipped cream, and berries until all ingredients are used, finishing with a final layer of whipped cream and berries on top.

7. Chill the trifle:
Cover and refrigerate the trifle for 2–3 hours (or overnight) to allow the flavors to meld and the dessert to set.