In a glass jar or airtight container, combine rolled oats, protein powder, chia seeds, and ground cinnamon.
Whisk or stir the dry ingredients until evenly distributed.
Pour in the almond milk and vanilla extract.
Stir vigorously to ensure the protein powder is fully dissolved and no dry clumps remain.
Fold in the almond butter.
Seal the container and refrigerate for at least 6 hours, preferably overnight.
Before serving, stir again and top with sliced almonds.