Preheat oven to 350°C. Line a 8x10 or 9x9 pan with parchment paper or rub the bottom and sides with coconut oil.
Add all blueberry filling ingredients except ground chia seeds to a saucepan. Cover, bring to a boil and then reduce and simmer for 10 minutes. Once finished cooking, place dates and ½ cup of the liquid into a food processor and blend until smooth. Add date mixture back to the sauce pan and add chia seeds. Mix until fully combined and store in refrigerator for 10 minutes so it can cool to room temperature.
Add all ingredients for the oatmeal bars into a large bowl and mix well until all ingredients are completely combined.
Line the pan with ½ of the oatmeal mixture, top with the blueberry filling and crumble the remaining oatmeal mixture over top.
Bake for 40-45 minutes. Keep it from crumbling by letting it cool completely before cutting.