1. 1. Combine Dry Ingredients: In a medium-sized jar or container with a lid, combine the rolled oats, vanilla protein powder, and chia seeds. Give them a quick stir with a spoon to ensure they are evenly distributed. This helps prevent the protein powder from clumping.

2. 2. Add Wet Ingredients: Pour in the milk, plain Greek yogurt, vanilla extract, and maple syrup (if using).

3. 3. Mix Thoroughly: Stir all the ingredients together very well. Use a spoon or a small whisk to ensure there are no dry pockets of oats or protein powder clinging to the bottom or sides of the container. The mixture should look consistently creamy.

4. 4. Fold in Berries: Gently fold in the 1/2 cup of mixed berries. You can stir them in completely or just lightly incorporate them so they are distributed throughout the mixture.

5. 5. Cover and Chill: Place the lid securely on your jar or container. Transfer it to the refrigerator and let it chill for at least 4 hours, but ideally overnight, for the best texture and flavor development.

6. 6. Serve and Garnish: In the morning, give the oats a quick stir. If they seem too thick, you can add a splash more milk to reach your desired consistency. Top with additional fresh berries, a sprinkle of granola, or a dollop of extra yogurt before serving.