To make the seed blend: combine all seeds and grind in a food processor until the husks are broken down and the mixture is a coarse powder. Store in a sealed jar in the fridge for up to one month.
To make the overnight oats: combine the oats, milk, chia seeds, ground seed blend, sweetener, vanilla, salt, and cinnamon in a wide-mouthed jar or container. Stir well to combine. If adding dried fruit or frozen berries, stir these in now.
Seal the jar and refrigerate overnight, or for a minimum of four hours.
In the morning, give the oats a good stir. Add a splash of extra milk if you prefer a looser consistency. Top with your choice of fresh fruit, nuts, yoghurt, or any of the topping combinations above.