Warm the berries in a pan over medium heat until the juices release and become bubbly. Gently mash with a spatula.
Remove from the heat and stir in the chia seeds. Leave to thicken for 10 minutes. It will set more as it cools. Note: for a smooth jam, you can blend it.
Transfer to a jar and store in the fridge for up to 5 days.
Store in the fridge for 5 days or freezer for 2 months