In a medium saucepan, combine the rolled oats, milk, pumpkin puree, maple syrup, pumpkin pie spice, vanilla extract, and salt.
Heat the mixture over medium heat, stirring frequently until it comes to a gentle simmer. This should take about 5 minutes.
Once the mixture is simmering, reduce the heat to low and cook for an additional 2-3 minutes, stirring continuously until the oatmeal thickens to your desired consistency.
Remove the saucepan from the heat and let it sit for a minute to cool slightly.
Spoon the oatmeal into each mason jar, filling them evenly.
Allow the oatmeal jars to cool to room temperature before sealing them with lids.
Store the oatmeal jars in the refrigerator for up to one week. When ready to eat, simply heat them in the microwave for about 1-2 minutes.