Begin by preheating your oven to 350°F (175°C). Prepare a muffin tin by lining it with paper liners or lightly greasing each cup with cooking spray or oil.
In a large mixing bowl, combine the whole wheat flour, almond flour, rolled oats, baking powder, baking soda, salt, and ground cinnamon. Use a whisk to mix the dry ingredients thoroughly and ensure there are no lumps.
In a separate bowl, whisk together the honey (or maple syrup), unsweetened applesauce, large egg, and vanilla extract until the mixture is smooth and well blended. This helps to incorporate air for fluffier muffins.
Gently pour the wet ingredients into the bowl containing the dry ingredients. Stir with a spatula or wooden spoon just until everything is combined—avoid overmixing, as a few lumps are perfectly fine.
Carefully fold in the fresh blueberries and chia seeds (if you choose to use them), ensuring to do so gently to prevent the blueberries from bursting.
Using a spoon or ice cream scoop, evenly distribute the muffin batter into the prepared muffin tin, filling each cup about ¾ full to allow room for rising.
Place the muffin tin into the preheated oven and bake for 18-20 minutes. They're done when a toothpick inserted into the center of a muffin comes out clean with only a few moist crumbs attached.
Once baked, remove the muffins from the oven and allow them to cool in the tin for 5 minutes. After that, transfer them to a wire rack to cool completely, which helps maintain a light texture.
Notes
Serve warm with a sprinkle of powdered sugar and a fresh blueberry on top.