For the Trifle Base
Pre-make 4 cups jelly liquid, set aside to cool but don’t refrigerate. Cover the bottom of a 3.5L trifle bowl with the strawberries and blueberries, keeping some aside for garnish. Pour half of the jelly liquid over the fruit in the trifle dish. Refrigerate uncovered for 1½ hours until partly set. Keep the remaining jelly liquid aside on the counter.

For the Custard
Place skim milk into a small saucepan over medium heat. Remove from heat just as it comes to a simmer. Meanwhile, in a large bowl, whisk the yolks, cornflour, sugar and vanilla. Gradually pour the hot milk onto the egg mixture, whisking constantly. Return the mixture to the saucepan over low heat. Simmer, stirring for 15 to 20 minutes or until custard thickens and coats the back of a metal spoon. Allow to cool.

For the Cake
Preheat oven to 180°C conventional or 160°C fan forced. Grease the inside of a 20x30cm slice pan and line the base with baking paper. Put the coconut flour, sugar and self raising flour into a medium bowl and stir well. In a separate small bowl, combine milk and egg yolks and whisk. In a third bowl, using electric beaters, whisk the egg whites until soft peaks form. Pour the milk mixture into the flour mixture and stir through using a spatula. Now, gently fold the whisked egg whites into the batter until just combined. Pour batter into the prepared pan and bake for 18-20 mins or until a skewer inserted into the centre comes out clean. Transfer to a wire rack to cool completely. Cut cake into 2.5cm cubes and divide into two batches.

To Assemble
Remove trifle bowl from fridge. Layer one half of the cake cubes on the top then spoon the custard over the cake layer and return to the fridge for 1 hour or until the surface has firmed. At the same time, put remaining jelly in the fridge to thicken, but not set. When ready, remove trifle and remaining jelly from fridge. Spoon the jelly over the custard layer then gently scatter remaining cake cubes, submersing them into the jelly. Return to the fridge to set completely, about 3 hours. Whip cream and vanilla with a hand or bench mixer until soft peaks form. Add low fat Greek yoghurt and continue to whip until combined. When ready to serve, top the trifle with a layer of cream, then the mint leaves, cherries and remaining berries.