Blend all ingredients in a high speed blender until completely smooth. Pour mixture into a sterilized jar and fill to about 1 cm from the top. Cover the jar loosely with a lid (do not tighten). Leave at room temperature for 8-12 hours or overnight then tighten lid and transfer to fridge.
Serve yogurt with a dollop of Worthy Vanilla Rhubarb jam and slices of banana.