In a mason jar or airtight container, mix together the rolled oats, almond milk, Greek yogurt, pumpkin purée, chia seeds, maple syrup, vanilla extract, and pumpkin spice.
Seal the jar or container and place it in the refrigerator. Let it sit for a minimum of 2 hours, but ideally overnight for the flavors to meld and the oats to soften.
When ready to eat, give the oats a good stir. Top with a bit of Greek yogurt or maple syrup and sprinkle with chopped pecans for a delightful crunch.