(optional: add 1-2 tablespoons lemon juice for a flavor booster)
Add frozen raspberries and water to a small sauce pot. Heat until the berries begin to break down and the mixture starts to simmer. Stir well and mash the berries as much as you like. Simmer, stirring constantly, for about 2 minutes to thicken. (You can use a blender or immersion stick, but I just used a fork.)
Remove from heat and add chia seeds and maple syrup (and lemon, if using).
Stir well and set aside for 15-30 minutes, or until thick. Taste and adjust sweetness to your liking, or add some more chia seeds/water to make it thicker/thinner. Let cool and serve! Store in a jar in the fridge for as long as you and the USDA thinks is safe.
(Mine was gone after 2 weeks, but would probably be safe to eat for much longer.)