Gather your container. Use a jar or lidded container with at least a 12–16 ounce capacity to allow room for stirring and toppings.
Stir the dry ingredients. Add oats, protein powder, pumpkin pie spice, chia seeds (if using), and a pinch of salt.
Mix to break up any clumps in the protein powder.
Add the wet ingredients. Pour in milk, spoon in pumpkin purée and Greek yogurt, then add vanilla and maple syrup. Stir thoroughly until no dry pockets remain.
Adjust consistency. The mixture should be thick but still pourable. If it seems pasty, add a splash more milk.
If it’s too thin, add 1–2 teaspoons more chia seeds.
Cover and chill. Seal the container and refrigerate for at least 4 hours, ideally overnight, to let the oats soften and flavors meld.
Stir and serve. In the morning, give it a good stir. Add toppings like pecans, pumpkin seeds, or extra cinnamon. Taste and adjust sweetness if needed.
Take it to-go. If you’re heading out, transfer to a portable jar and top just before eating to keep crunch intact.