Add the sponge ingredients to a bowl and whisk until smooth, then spoon into a large microwave safe mug and microwave for 2 minutes (see notes) until springy to the touch.
Set aside to cool.
Once the sponge is cool top it with the fruit juice, then a layer or fruit.
Now add the ready-made jelly, smooch it a bit before adding the next layer.
Next, add the layer of custard.
Finish with a layer of whipped (or squirty) cream and sprinkles.
Enjoy!
Notes
I made a large trifle, which is enough for two I recommend, dividing the sponge and other ingredients into two smaller glasses.
My microwave is 800 watts. If yours is stronger the cake will be baked quicker than 2 minutes.
You can make up vegan jelly with jelly powder but it works really well with ready-made jelly.