Combine the Dry Ingredients: In a large mixing bowl, measure out your rolled oats, chia seeds, ground cinnamon, and a tiny pinch of sea salt. Give them a good stir with a spoon until they are well combined, ensuring the spices are evenly distributed. The mixture should look uniform, with the tiny chia seeds dispersed throughout the larger oat flakes.

Whisk in the Wet Ingredients: Pour in the milk, Greek yoghurt, maple syrup (or honey), and vanilla extract. Whisk everything together thoroughly. You're aiming for a smooth, homogenous mixture with no dry pockets of oats or chia seeds clinging to the bottom. The consistency should be pourable, a pale, creamy beige colour, and you might notice a subtle, sweet, vanilla-scented aroma starting to emerge.

Add Your Berries: Gently fold in your mixed berries. If using frozen berries, there's no need to thaw them completely; they’ll release their juices and vibrant colour as they chill. The mixture will now have beautiful streaks of red, purple, and blue throughout, adding a visual pop and fruity sweetness.

Portion and Cover: Divide the mixture evenly among four individual airtight containers or jars (I often use wide-mouth mason jars for this). Ensure each container is filled to a reasonable level, leaving a little space at the top. Securely place the lids on each container.

Chill for Transformation: Place the covered containers in the refrigerator. Allow them to chill for a minimum of 4 hours, though overnight (8-12 hours) is truly ideal. This extended chilling time allows the oats and chia seeds to fully absorb the liquid, swelling and softening, transforming the mixture from a liquid batter to a thick, creamy, pudding-like consistency. You’ll know they’re ready when the liquid has been almost entirely absorbed, and the oats have a soft, plump texture.

Serve with Toppings: When you're ready to serve, pull a jar from the fridge. Open the lid and give the oats a quick stir. If desired, top with your chosen chopped nuts, fresh banana slices, or an extra drizzle of maple syrup. The oats will be cool, creamy, and wonderfully fragrant with hints of fruit and cinnamon, ready to be enjoyed straight from the jar.