Prepare the Oat Base: In a large mixing bowl, whisk together the rolled oats, chia seeds, hemp hearts, 1 ½ teaspoons of cinnamon, nutmeg, and allspice. Pour in the oat milk and 3 teaspoons of vanilla extract. Stir thoroughly until no dry spots remain. Set aside to thicken while you prepare the apples.
Sauté the Apples: Place a medium non-stick skillet over medium heat. Add the diced apples, 1 tablespoon of honey, 1 teaspoon of cinnamon, and the pinch of sea salt. Stir to coat the apple pieces evenly.
Simmer until Tender: Cook the apple mixture, stirring occasionally, for 6 to 8 minutes. The apples should become fork-tender and the liquid will reduce to a thick, syrupy glaze that clings to the fruit. Once tender, remove the skillet from the heat.
Layer the Jars: Get four 16-oz (475 ml) sealable jars. Divide half of the creamy oat base evenly among the jars. Spoon the warm sautéed apple mixture over the oats, creating a distinct layer in each jar.
Add the Final Layers: Carefully top the apple layer with the remaining oat base, distributing it equally. Sprinkle the chopped pecans evenly over the top of each jar.
Chill and Set: Seal the jars with their lids and place them in the refrigerator for at least 8 hours, or overnight. This resting period allows the oats and chia seeds to fully absorb the liquid and develop a rich, pudding-like consistency. Serve chilled.