01 - Combine strawberries, blueberries, raspberries, and sugar in a medium bowl. Toss gently and let sit for 10 minutes until juices are released.
02 - In a large mixing bowl, whip heavy cream to soft peaks. Add mascarpone or cream cheese, granulated sugar, and vanilla extract. Continue whipping until mixture is smooth and thick.
03 - If making vanilla custard from scratch, prepare according to your preferred method and let cool to room temperature.
04 - Place half of the cake cubes in the base of a trifle bowl or serving glasses, forming an even layer.
05 - Spoon half of the macerated berries with their juices over the cake cubes.
06 - Spread half of the vanilla custard over the berry layer, then top with half of the vanilla cream mixture.
07 - Repeat with remaining cake cubes, berries, custard, and vanilla cream to create a second set of layers.
08 - Arrange extra fresh berries and mint leaves on top as an optional garnish.
09 - Refrigerate for at least 1 hour before serving for flavors to meld and dessert to set.