Mix the smooth ingredients. Whisk the yogurt, pumpkin, milk, maple syrup, spice and vanilla in a large bowl. Break up any pockets of pumpkin so the flavor is evenly distributed.
Add the oats and chia. Stir thoroughly, scraping the bottom of the bowl. Let stand for five minutes, then stir again to separate any clumps of chia seeds.
Divide into four portions. Use covered food containers or wide-mouth jars. Leave some headroom so you can stir the oats and add toppings.
Refrigerate immediately. Chill at 40°F or below for at least eight hours. Overnight soaking happens in the refrigerator, not on the countertop.
Adjust before eating. Stir each serving. Add milk a tablespoon at a time if it is too thick, then add your preferred toppings.
Storage: For this recipe, plan to eat the prepared oats within 3–4 days in a refrigerator at 40°F or below, following any shorter ingredient instructions. Label the containers with the preparation date. Keep them cold during transport and refrigerate on arrival. USDA’s safe storage guidance explains prompt refrigeration and the two-hour limit for perishable food, reduced to one hour above 90°F.