In a jar or airtight container, combine 1/2 cup whole rolled oats, 1 tablespoon chia seeds, 1/2 teaspoon maple syrup, a pinch of sea salt, and (optional) 1/4 cup Greek yogurt.
Pour in 2/3 cup unsweetened almond milk and stir thoroughly until all dry ingredients are evenly moistened and there are no dry pockets of oats or chia.
Seal the jar or container with a lid.
Refrigerate overnight (at least 6 hours) to allow the oats and chia to soften and thicken.
In the morning, remove from the fridge and stir to combine; if the mixture is thicker than you prefer, stir in a small amount of additional almond milk to loosen.
Top with your choice of assorted toppings (e.g., diced apple, chopped nuts, fresh berries, banana slices, chocolate chips) and drizzle extra maple syrup to taste.
Serve and enjoy.