Choose your container. A 12–16 oz jar or lidded container works best so you have room to stir and add toppings.
Mix the wet ingredients. Add milk, Greek yogurt, peanut butter, vanilla, and sweetener to the container. Stir until smooth. If your peanut butter is thick, microwave it 10–15 seconds first so it blends easily.
Add the dry ingredients. Stir in protein powder, cocoa powder, and a pinch of salt until combined.
Make sure there are no dry pockets—this prevents a chalky texture.
Add oats (and seeds if using). Fold in the oats and chia or flax. The mixture should look loose; it will thicken overnight as the oats and seeds absorb liquid.
Adjust the consistency. If it seems too thick already, add 1–2 tablespoons more milk. If very runny, add an extra teaspoon of chia seeds.
Refrigerate. Seal and chill for at least 4 hours, ideally overnight.
The flavor deepens and the texture becomes creamy.
Serve. In the morning, give it a stir. Add a splash of milk if needed. Top with sliced banana, chopped peanuts, or a drizzle of peanut butter.
Enjoy cold, or warm gently in the microwave in 20–30 second bursts, stirring in between.