In a sealable jar or container, combine almond milk, Greek yogurt, rolled oats, protein powder, chia seeds, mashed banana, and vanilla extract. Stir until well mixed.
Choose your desired flavor variation and add those ingredients into the mixture.
Seal the jar tightly and refrigerate overnight or for at least 6 hours.
When ready to serve, stir in more almond milk if needed and add your favorite toppings.