Place the sliced strawberries in a bowl and sprinkle with sugar. Mix gently and let sit for about 10 minutes to macerate, allowing the strawberries to release their juices.
In a separate large mixing bowl, whip the heavy cream until soft peaks form. Add vanilla extract and continue whisking until combined but not overwhipped.
Prepare the vanilla pudding according to package instructions if using instant pudding, or make your own if preferred.
In your trifle bowl or individual serving glasses, start layering. Begin with a layer of sponge cake cubes.
Spoon some vanilla pudding over the sponge cake to cover it.
Add a layer of the macerated strawberries, followed by a layer of whipped cream.
Repeat the layering process until all ingredients are used, finishing with a layer of whipped cream on top.
Garnish with additional slices of strawberries and mint leaves if desired.
Chill in the refrigerator for at least 1 hour before serving to allow flavors to meld.