Prepare the Base Mixture: In a large bowl, combine the rolled oats, protein powder, chia seeds, maple syrup (or honey), and a tiny pinch of salt. Use a whisk to ensure the protein powder is well distributed, so you don't end up with any powdery pockets later on. The dry ingredients should look uniformly mixed.

Add the Liquid: Pour in the milk gradually, stirring continuously with the whisk. Continue mixing for about 1-2 minutes until all the dry ingredients are thoroughly hydrated and there are no clumps of oats or chia seeds clinging to the bottom of the bowl. The mixture will appear quite liquidy at this stage, a pale, milky colour with suspended oats.

Divide the Base Mixture: Evenly divide the base oat mixture into three separate airtight containers or jars. This foundational step ensures each flavour starts with the same creamy consistency. The mixture will still be quite fluid, but you’ll see the oats beginning to swell slightly.

Create the Berry Burst Flavour: To one container, add the mixed berries (if using frozen, they'll thaw beautifully overnight) and the vanilla extract. Stir gently until the berries are evenly distributed throughout the oats, imparting a lovely pinkish-purple hue. Ensure the vanilla aroma is present.

Develop the Chocolate Hazelnut Flavour: In the second container, add the cocoa powder, chopped hazelnuts, and hazelnut butter. Stir thoroughly until the cocoa powder is completely dissolved and the mixture transforms into a rich, dark brown colour. You might notice a subtle nutty aroma already.

Assemble the Spiced Apple Pie Flavour: For the third container, mix in the grated or finely diced apple, ground cinnamon, and mixed spice. Stir well until the spices are evenly distributed, giving the oats a warm, inviting brown shade and releasing a fragrant, autumnal aroma.

Chill Overnight: Securely place lids on all three containers. Refrigerate for a minimum of 6 hours, or ideally overnight. When you check them in the morning, the oats should have absorbed most of the liquid, resulting in a wonderfully thick, creamy, and pudding-like texture.

Serve and Enjoy: The next morning, give each container a quick stir. If the mixture is too thick for your liking, you can add a splash more milk to reach your desired consistency. Top with additional fresh fruit, nuts, seeds, or a dollop of nut butter as desired, and enjoy your delicious, high-protein breakfast!