Combine rolled oats, protein powder, and chia seeds in a 16-ounce glass jar or airtight container.

Stir the dry ingredients until the protein powder is evenly distributed through the oats.

Add the Greek yogurt, almond milk, vanilla extract, and maple syrup to the jar.

Stir vigorously with a spoon or seal the jar and shake until no dry clumps of protein powder remain.

Seal the container and refrigerate for a minimum of 6 hours, ideally overnight (8 hours).

Remove from the refrigerator and stir to check consistency; add a splash of milk if a thinner texture is desired.

Top with fresh blueberries immediately before serving.