01 - Combine strawberries, blueberries, raspberries, and sugar (if using) in a medium bowl. Toss gently and let stand for 10 minutes to release juices.
02 - In a large mixing bowl, whip heavy cream to soft peaks. Add mascarpone or cream cheese, granulated sugar, and vanilla extract. Whip until smooth and thick.
03 - If preparing custard from scratch, cook and cool according to your preferred method. Use prepared vanilla pudding if desired.
04 - Arrange half of the cubed cake in the base of a trifle bowl or individual serving glasses.
05 - Spoon half of the macerated berries and their juices over the cake cubes.
06 - Spread half of the custard over the berries, followed by half of the vanilla cream mixture.
07 - Repeat with the remaining cake, berries, custard, and cream, creating distinct layers.
08 - Top with extra berries and fresh mint leaves if desired. Chill the trifle for at least 1 hour before serving to enhance flavors.