Awaken the Nuts: Place the chopped pecans in a small, dry skillet over medium heat. Toast for 3-5 minutes, tossing frequently, until they become fragrant and lightly browned. Remove from heat immediately and set aside to cool.
Combine the Dry Staples: In a medium mixing bowl, add the rolled oats, chia seeds, and pumpkin pie spice. Stir with a fork to distribute everything evenly.
Create the Flavor Base: In a separate, smaller bowl, peel and mash one full banana until it forms a smooth pulp. Add the date paste and vanilla bean paste, whisking vigorously until the mixture is uniform and creamy.
Hydrate the Base: Pour the unsweetened almond milk into the banana mixture. Whisk thoroughly until the base is smooth and fully liquefied.
Marry the Mixtures: Pour the wet banana-milk mixture into the bowl with the dry oat blend. Use a silicone spatula to fold everything together until no dry spots remain. Stir in about three-quarters of the toasted pecans, reserving the rest for garnish.
Portion and Chill: Divide the oat mixture evenly among the three jars. Seal the lids tightly. Transfer the jars to the refrigerator to set for a minimum of 6 hours, or preferably overnight, until the mixture has thickened to a pudding-like consistency.
Garnish and Serve: When ready to eat, slice the remaining half banana. Top the chilled oats with the fresh banana slices and the reserved toasted pecans. Enjoy directly from the jar.