In a medium bowl, mix oats, milk, yogurt, honey or maple syrup, vanilla extract, and salt until well combined.
In a separate bowl, mash raspberries with a fork, then stir in chia seeds, water, and honey if using. Let sit for 5 minutes to thicken.
Divide half the oat mixture evenly between two jars or containers.
Add a layer of the raspberry chia mixture on top of the oats.
Top with the remaining oats and seal containers with lids.
Refrigerate for at least 8 hours or overnight.
Before serving, gently stir oats and top with fresh raspberries and sliced almonds or granola as desired.