Heat oven to 350F degrees. Prepare a 12 muffin tin pan, lining each muffin cup with muffin papers, or spray with coconut oil nonstick cooking spray.
In a large bowl whisk together coconut flour, salt, baking powder, and cinnamon. Create a well in the center of the dry ingredients and add the eggs, vanilla, maple syrup, erythritol, coconut milk and coconut butter.
Whisk together the liquid ingredients in the center and then whisk in the dry ingredients. Keep whisking for 1-2 minutes or use a handheld electric mixer.
Fold in the blueberries and let the mixture sit for 5 minutes. The batter will thicken as the coconut flour absorbs the liquid.
Combine all ingredients for the topping if desired and set aside.
Using a spoon, evenly distribute muffin batter between 12 muffin cups in the tin.
Sprinkle the topping (if using) evenly on each of the muffins.
Bake for 35 minutes and serve warm.