Mix together the oats, yoghurt, grated apple, granulated sweetener and vanilla extract
Place this mixture in the bottom of a Kilner jar (the jar should be able to hold up to 350ml)
Spread the blackcurrants over the top of this layer
In a clean bowl, mix together the "custard" ingredients - yoghurt, quark, vanilla extract, chia seeds and granulated sweetener. Beat it well to remove any lumps. You could add a drop of yellow food colouring to add a custardy colour.
Pour this mixture on top of the blackcurrants, close the lid and refrigerate overnight