Prepare the filling: In a mixing bowl, combine blueberries, chia seeds, honey (or maple syrup), lemon juice, vanilla, and a pinch of salt. Stir well and let it sit for 10–15 minutes to allow the chia to thicken naturally.
Preheat the oven: Set your oven to 180°C (350°F) while the chia mixture rests. Lightly grease a baking dish with a bit of coconut oil or butter.
Make the crumble topping: In a separate bowl, mix rolled oats, almond flour, melted coconut oil, honey, cinnamon, and salt. Combine until crumbly the mixture should hold together slightly when pinched.
Assemble the crumble: Pour the blueberry filling into the prepared dish, spreading it evenly. Sprinkle the oat-almond crumble on top, making sure to cover the fruit without pressing it down.
Bake to perfection: Bake for 30–35 minutes, or until the top turns golden brown and the blueberry filling bubbles around the edges.
Cool slightly and serve: Let the crumble rest for 10 minutes before serving. Enjoy it warm or chilled it’s delicious both ways.