Prepare the Dry Base In the large mixing bowl, add the rolled oats, chia seeds, cinnamon, ginger, nutmeg, cardamom, and the pinch of sea salt. Whisk everything together until the spices are evenly distributed throughout the oats.
Blend the Pumpkin Cream In a separate liquid measuring cup or medium bowl, combine the Icelandic skyr, pumpkin purée, oat milk, date syrup, and vanilla bean paste. Whisk vigorously until the mixture is smooth, creamy, and uniform in color.
Unite the Mixtures Pour the liquid pumpkin cream mixture over the dry oat base in the large bowl.
Incorporate Thoroughly Using a silicone spatula, fold the ingredients together. Scrape the sides and bottom of the bowl to ensure no dry pockets of oats remain and the mixture is fully combined.
Portion and Seal Carefully divide the oat mixture evenly among the three jars. Seal each jar securely with its lid.
Chill and Set Transfer the sealed jars to the refrigerator. Allow them to chill for a minimum of 6 hours, or until the oats have absorbed the liquid and the mixture has thickened to a spoonable, pudding-like consistency. Serve chilled, with toppings like toasted pecans, a dollop of skyr, or a sprinkle of cinnamon.