Preheat the oven to 425 degrees Fahrenheit.
Place the flour, cornmeal, cinnamon, baking soda and salt in a bowl and whisk.
Add the wet ingredients one by one (except the blueberries) and, using a spatula, mix them until just combined and no traces of dry flour are visible. This is a thick batter, scoopable but not pourable. But if it is too dry, you can add a little more milk.
Stir in the blueberries at the end, then scoop the batter equally into the cups of a 12-cup muffin pan. Sprinkle some sugar on top of each muffin.
Place the muffin can in the hot oven and bake 25 minutes.
Allow the muffins to cool for five minutes before removing them from the pan.