Combine rolled oats, almond milk, pumpkin puree, Greek yogurt, maple syrup, chia seeds, pumpkin pie spice, vanilla extract, and salt in a 16-ounce glass jar.
Stir the ingredients thoroughly with a spoon or seal the jar and shake until the mixture is completely homogenous.
Secure the lid tightly and refrigerate the container for a minimum of 6 hours, or ideally overnight, to allow the oats and chia seeds to fully hydrate.
Before consumption, stir the oats to redistribute moisture and adjust consistency with an additional splash of milk if desired.
Serve chilled, optionally garnished with crushed pecans or a dusting of cinnamon.