Preheat your oven to 35°F (180°C) and grease a baking dish with butter.
In a large mixing bowl, combine the oatmeal, coconut sugar, coconut flour, and chia seeds.
In a separate saucepan, bring the water to a boil, then add it to the oat mixture and stir well.
Pour in the plant milk, maple syrup and mix until all the ingredients are thoroughly combined.
Gently fold in the blueberries, ensuring they are evenly distributed throughout the mixture.
Transfer the oatmeal mixture to the greased baking dish and smooth the top with a spatula.
Dot the surface of the oatmeal with small pieces of dairy-free butter for added richness.
Place the dish in the preheated oven and bake for 35-40 minutes, or until the top is golden brown and the oatmeal is set.
Once baked, remove from the oven and let it cool for a few minutes before serving.