Add the water or milk, Medjool dates, peanut butter, banana, cinnamon, vanilla extract, and a pinch of salt to a high-speed blender or food processor. Blend until completely smooth and creamy with no date pieces remaining.

Place the old fashioned oats into 3–4 airtight containers for meal prep, or add them all into one large container.

Pour the blended mixture evenly over the oats and stir well until fully combined and coated.

Cover and refrigerate for at least 2 hours, preferably overnight, until the oats are soft and thickened.

Stir before serving and enjoy cold. Store covered in the refrigerator for up to 5–7 days for best freshness.