Pour the fruit and maple syrup into a small saucepan over medium-high heat. Bring the fruit to a simmer, gently pressing it with fork or spatula to help it break down.
Let the fruit and maple syrup simmer together for 5 to 7 minutes, until the fruit is totally broken down. It should thicken slightly, but it will still be slightly runny after 7 minutes. That's exactly how it should be!
Remove from the heat, then stir in the chia seeds. Pour the chia seed jam into an airtight glass jar, and let the jam chill in the fridge until thickened, at least 4 hours. This recipe makes roughly 6 ounces of jam, but it can make slightly less than that depending on how long you let the fruit juices simmer and evaporate.
Homemade jam can be stored in an airtight container in the fridge for up to 1 week, or you can freeze it for up to 3 months. I do not recommend canning it for safety reasons. (See the post above for details.)
You can add more or less maple syrup to this recipe, so feel free to adjust it to your taste. If you don't need a vegan recipe, you can also try using honey as the sweetener, instead.