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.
02 - Heat the whole milk until steaming in a saucepan. Whisk egg yolks with granulated sugar and cornstarch until smooth. Gradually pour hot milk into the yolk mixture while whisking constantly. Return everything to the pan and cook over medium heat, stirring continuously, until thickened. Remove from heat, stir in vanilla extract, and let cool completely.
03 - Combine mixed berries with granulated sugar and lemon juice in a bowl. Let sit for 10 minutes to allow berries to release their juices and create a syrupy consistency.
04 - Beat heavy cream, powdered sugar, and vanilla extract together until soft peaks form. Be careful not to overwhip.
05 - Layer half the custard over the soaked cake base. Spoon in half the macerated berries followed by half the whipped cream. Repeat layers with remaining cake cubes, custard, berries, and whipped cream, ending with whipped cream on top.
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 together.