Combine chia seeds and spinach with the frozen blackberries and cherries, and pour the milk on top. Blend on high till smooth, then add in ice to thicken, if needed.
Notes
If your blackberries are really tart or you think you need some extra sweetener try 1 teaspoon lucuma powder, honey, or maple syrup.
Dried mulberries would go great here as well, if you have them on hand.