Preheat the oven to 200° C
In a big bowl, whisk the flour, baking powder, baking soda, salt, and cinnamon.
In a seperate bowl, whisk the coconut oil, coconut sugar, eggs, Greek yogurt and vanilla extract.
Gently fold the wet ingredients into the dry ingredients. Once mixed, fold in the blueberries with a wooden spoon or spatula.
Pour into the muffin pan, either filled with muffin cups or oiled. Fill them 3/4 of the way high.
In a small bowl, mix the cinnamon and sugar for the topping. Then sprinkle each muffin with a bit of this mixture.
Bake for 16-20 minutes, keeping your eye on them. The tops should be golden and the inside should be cooked through (duh). Feel free to poke them with a toothpick or knife to check for doneness.
Remove the muffins from the tin and let them cool on a wire rack until they're still warm but not hot enough to burn the roof of your mouth.