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 the milk in a saucepan until steaming. Whisk egg yolks with sugar and cornstarch until smooth. Gradually pour hot milk into the yolk mixture while whisking constantly to prevent curdling. Return everything to the pan and cook over medium heat, stirring continuously until thickened. Remove from heat, stir in vanilla, and cool completely.
03 - Combine mixed berries with sugar and lemon juice in a bowl. Let sit for 10 minutes to allow the berries to release their juices and create a natural syrup.
04 - Whip the heavy cream with powdered sugar and vanilla extract using an electric mixer or whisk until soft peaks form. Be careful not to overwhip.
05 - Layer half the custard over the cake base, then spoon in half the macerated berries. Add half the whipped cream. Repeat layers with remaining cake, custard, berries, and whipped cream, creating distinct visual layers.
06 - Decorate the top with chocolate eggs, colored sprinkles, and fresh mint leaves if desired. Refrigerate for at least 2 hours before serving to allow flavors to meld and layers to set.