01 - Combine strawberries, blueberries, raspberries, and sugar (if using) in a medium bowl. Toss gently and set aside for 10 minutes to let the berries release their juices.
02 - In a large bowl, whip heavy cream to soft peaks. Add mascarpone or cream cheese, granulated sugar, and vanilla extract. Continue whipping until the mixture is thick, smooth, and fully combined.
03 - If preparing homemade custard, cook according to your preferred method and allow it to cool completely before layering.
04 - Arrange half of the cubed cake in the base of a trifle bowl or individual serving glasses.
05 - Spoon half the macerated berries with their juices over the cake. Evenly spread half the vanilla custard, followed by half the vanilla cream mixture on top.
06 - Repeat with remaining cake cubes, berries, custard, and vanilla cream to create a second set of layers.
07 - Top with extra fresh berries and mint leaves if desired. Refrigerate for at least 1 hour before serving to allow the flavors to meld.