01 - Cube the sponge cake or ladyfingers and arrange half in the base of a large trifle dish. Sprinkle with orange juice or sherry if using for added moisture and flavor.
02 - Heat milk until steaming in a saucepan. Whisk egg yolks with sugar and cornstarch until smooth. Gradually pour hot milk into yolk mixture while whisking constantly. Return to pan and cook over medium heat, stirring continuously until thickened. Remove from heat, stir in vanilla, and let cool completely.
03 - Combine mixed berries with sugar and lemon juice in a bowl. Let stand for 10 minutes to allow berries to release their natural juices and create a flavorful syrup.
04 - Whip heavy cream, powdered sugar, and vanilla extract together until soft peaks form. Be careful not to overwhip as cream should remain light and fluffy.
05 - Spread half the custard over the cake base. Spoon half the macerated berries over the custard, followed by half the whipped cream. Repeat layers with remaining cake cubes, custard, berries, and whipped cream.
06 - Decorate the top with chocolate eggs, colored sprinkles, and fresh mint leaves if desired. Refrigerate for at least 2 hours to allow flavors to meld and dessert to set properly before serving.