Preheat oven to 425F degrees. Spray muffin tin with non-stick spray or line with muffin liners.
In a large bowl, lightly mix flour, baking powder, salt, and cinnamon until combined.
In a medium bowl, whisk together eggs and sugar until combined. Add milk, oil, and vanilla. Fold wet ingredients into dry ingredients and mix everything together (no mixer). Don't overmix. Gently mix until all the flour is off the bottom of the bowl and no big pockets of flour remain. The batter will be VERY thick and somewhat lumpy. Fold in the blueberries.
Pour batter into prepared muffin tins all the way to the top. Bake at 425F degrees for 5 minutes. Reduce oven temperature to 375 and continue to bake for 25-26 minutes until tops are lightly golden and centers appear set.