Combine Ingredients: In a mason jar or bowl, mix the rolled oats, almond milk, chia seeds, honey (if using), vanilla extract, and salt.
Add Berries: Gently fold in the mixed berries, reserving a few for topping later.
Refrigerate: Cover the jar or bowl and refrigerate overnight (or at least 4 hours) to allow the oats and chia seeds to absorb the liquid and soften.
Serve: In the morning, give the oats a good stir, and add a splash of milk if they seem too thick. Top with additional mixed berries, and enjoy!