In a mason jar or airtight container, combine the rolled oats, almond milk, Greek yogurt, maple syrup, cinnamon, vanilla extract, and salt. Stir thoroughly until all ingredients are evenly mixed and no dry oat pockets remain.
Gently fold in the diced peaches, distributing them throughout the oat mixture. Reserve a few peach pieces to place on top if desired for a prettier presentation.
Seal the container tightly with a lid and refrigerate for at least 6 hours, or overnight for best results. The oats will absorb the liquid and become creamy and thick.
In the morning, give the oats a good stir. If the mixture seems too thick, add 1-2 tablespoons more almond milk and stir until you reach your preferred consistency.
Enjoy cold straight from the fridge, or microwave for 45-60 seconds for a warm breakfast. Top with additional fresh peach slices, a sprinkle of cinnamon, granola, or crushed graham crackers before serving.